Just posting my results so that it might help others...
No problems upgrading a Dell GX280 2.8Ghz machine with 1gb of ram to Windows 7Pro/Ultimate 32 bit. From a wiped and reformatted 40gb drive the install went flawlessly.
Graphics were working but there was a ? in device manager for missing drivers. There was also no audio.
The audio drivers for Vista (R145551.exe) on the Dell support site worked perfectly after a manual install.
www.dell.com/.../DriversDetails
For the graphics I used the (sp34749.exe) drivers suggested elsewhere on this site. Full graphics at all resolutions after this manual install.
http://ftp.hp.com/pub/softpaq/sp34501-35000/sp34749.exe
Other than this, I had to manually install nothing else. NIC drivers were present after Win 7 install..