"Modern" IBM PCs
On this page, the term "modern" is used loosely... extremely loosely. The models described within this page are, at the very least, 12 years old. IBM sold their PC Division to Lenovo, a Chinese computer manufacturer, in 2005. IBM also provided branding rights to the IBM logo and name for three additional years afterwards, until Lenovo started branding all former IBM products (ThinkPad, ThinkCentre, etc.) as Lenovo products.
There were many great products constructed by IBM that was spun off of some version of the PS/2 series. The P70, released in 1989, and its cousin, the P75 (1990), both inspired the ThinkPad line. The Note (N33 and N51 - both from 1991) heavily influenced the design of the ThinkPad, as the N33 was the first notebook computer produced by IBM. (The P70/P75 were both luggables, as was the PC Convertible from 1986.)
However, the ThinkPad was not the only other product inspired by the PS/2 line. The PS/2e was an energy efficient version of the PS/2 which was intended to only consume 24 watts. The PS/2e weighed 4kg (8 pounds), and was made of recycled plastics, designed to be easily recyclable when it reached the end of its life. The PS/2e also borrowed many components from the ThinkPad, including the floppy and hard drives. The PS/2e also typically shipped with a smaller keyboard (without the numeric keypad, similar to a laptop keyboard) that included an early version of the TrackPoint.
The PS/2 series also inspired the PS/ValuePoint series. IBM's PS/2 was unable to compete in the home market, similar to the PC 5150, because of its price. Competitors (especially PC clone manufacturers) were releasing products that cost a fraction of what IBM wanted for similar equipment. The PS/ValuePoint (PS/VP - or just Value Point or VP) was the answer to the competition issues. These computers relied on the 386SLC-25, which was an IBM/Intel processor. However, other models used the 486SX-25, 486DX-33, 486DX2-66, and even the Pentium 60 - all genuine Intel products. The PS/VP was introduced in October 1992, but was discontinued in July 1995.
The PC Series
The PC Series is somewhat of a confusing name. IBM sold the PC line from 1981 to 1986, and it is easy to get the two lines mixed up.
The first notable PC Series computer was the PC-330. This was one of the first systems to utilize USB, which was an "up-and-coming" invention at the time. The 330 used genuine Intel processors, and came with an OS ranging from Windows 2000 to Windows ME. Windows XP *can* be installed, but the system will slow down considerably.
The Aptiva was the replacement for the IBM PS/1. Both were intended to be competitors in the home market, to compete with PC clones aimed at budget-concious consumers, as well as low-end models from other manufacturers, namely Apple with their Macintosh LC series and later compact Mac (Classic, etc.) lines.
The Aptiva got off to a rocky start. IBM developed the Lotus SmartSuite, including the infamous Lotus 1-2-3 spreadsheet program. In addition to Lotus software, Big Blue developed OS/2 for the PS/2. OS/2 was a prime competitor to Microsoft Windows, and Lotus SmartSuite was competing against Microsoft Office. Naturally, Bill Gates did not take kindly to this fact.
In a mean (and considerably risky) business move, Microsoft placed restrictions on IBM. Microsoft charged IBM with higher prices for their products, not providing technical and marketing support, and a late license for IBM. This was a real kick in the pants for IBM, as other companies - such as Dell, Gateway 2000, and HP, had access to Windows 95 when it was in its RTM (release-to-manufacturing) stage for OEMs. IBM was not granted OEM rights to Win95 until a mere 15 minutes before Windows 95 was released to the public.
This did not help IBM's sorry state at the time. IBM fell during the late 1980s, especially after PC clone manufacturers stole a considerably large chunk of their market share away from them. IBM never got back the market share, and by this time the ThinkPad was their only product that put IBM in the running.
Post-2000 (NetVista, IntelliStation, and ThinkCentre)
The IntelliStation was a higher-class workstation introduced by IBM in 1997. While many models utilized genuine Intel processors, there were some models that relied on IBM's own POWER processors. The IntelliStation was probably the last personal computer series manufactured by IBM themselves, as it was not discontinued until 2009, and was not included in the sale to Lenovo.
The NetVista was a variety of computers, aimed at small-business and POS (point-of-sale) use. They ranged from kiosk computers, PCs (based on the PC Series; see above), and Network Stations. (Later versions of the NetVista series share the same design language that was used on the IBM ThinkCentre models.)
Last, but not least, the ThinkCentre. IBM enjoyed a lot of sucess with their ThinkPad line of products. It carried their PC division throughout the 1990s, and was a product which was so well engineered and built that it is still sold. (It may very well be one of the longest running PC models.) So, why not build off of that? They did just that with the ThinkCentre. Down to the matte-black plastic finish, and the business stature, the ThinkCentre was the desktop version of the ThinkPad. While it was introduced in 2003, Lenovo still makes current versions of the ThinkCentre to this very day.
Similar to the modern ThinkCentre line (by Lenovo), IBM sold two different form factors of the ThinkCentre. The tower form factor (shown left) is the more common of the two, whereas the desktop form factor (shown right) is much more compact.
While not a subject of personal computing, the POS (point-of-sale) part of IBM was another large use for their computers. IBM POS systems can be found in restaurants, Wal-Mart stores, and even small businesses. IBM sold their POS business recently to Toshiba in 2012 for $850 million.