Hi, I'm running a Sony Vaio SZ 23GP, which is basically the Asian version of your laptop. I recently upgraded to Windows 7 Ultimate, and had the exact same problems you did. Took me 2 days, and sifting through tons of forum posts to get everything working.
Here's what you need to do:
1) Most of the unknown devices are stuff such as the webcam, memory stick reader etc.
2) 2 important devices listed as "Unknown" are the Sony Notebook Controller (called Sony NC) and the Sony Programmable I/O Device. You need to download
drivers and manually install them via device manager. These are needed to get the FN keys, S1, S2 key and the brightness/ volume keys to work as they did in XP. You can recognize these devices, as they are not connected to the USB bus, unlike the webcam etc.
3) Sony did not really release Vista/Win 7
drivers for the SZ 2 series. You need to find the Vista
drivers for the newer SZ models, and use these. Your XP drivers won't work.
4) For the Go 7400 card, download an SZ Vista
driver from the Sony support site. Choose a newer model, but one that's not too new. SZ 4 series seems to work well. The
driver package won't install since there's a model check, so use a universal extractor to rip out the nvidia installer. That shld solve your problem.
5) Install Sony utilities such as the shared library, Vaio Event service etc. to restore your FN keys.
Hope this helps. Its a lot of hard working getting the laptop to function as it did in XP... but its possible.