I'm going to be Mister Never Had Vista, and I think I'm not going to be alone!
Now that Windows 7 is officially available, I decided I'd better start learning something about it. I have an IBM ThinkPad T-43 with one gig of memory and a tiny 30G hard disk. I decided to put Windows 7 Professional on it to See What Happens (tm).
I was using a "generic" Windows 7 install, and not one customized for the ThinkPad, and that made me worry that things like the eraserhead pointing stick might not work. However, the installation worked like a champ and all was well at the end. Apparently Lenovo (or IBM) provided Microsoft with at least a basic driver kit. Good.
I downloaded ThinkVantage System Update (TVSU). It took several iterations before I had everything up to date. Apparently TVSU understands prerequisites, but makes one iterate over them. That doesn't seem too bad as it only has to happen once. TVSU for Windows 7 can be downloaded here.
The only real problem I had is that TVSU tried to install an unsupported External Controller flash on my 1871-type T-43. I had to borrow a USB floppy and do a flash from diskette to get over that. Happily, it didn't brick my T-43.
I wish I had not installed ThinkVantage Access Connections. Windows 7 does a lot of what one needed Access Connections for. That's OK, too, because installing Windows 7 was an experiment. I intend to blow the installation away and start over in a month or so. (And yes, I did keep good notes.)
In summary, Windows 7 works even on older Thinkpads, and, with enough updates, you will get the drivers you need. (But please don't try this with a mission-critical machine, OK?)