I recently installed Win7 on a Dell Dimension 4400 running WinXP. It's up and running fine, here are some of the issues I ran into. 1.) The Dimension 4400 came with a CD and I needed to buy a cheap $29.00 DVD drive and install it. 2.) The network card was not recognized and neither was the sound card card so I needed to open up the Dimension Box again to get the make and model number off the cards so I could install the proper drivers from Dell. 3.) I saved my old emails and contacts from Outlook XP, when I reinstalled Outlook XP, I couldn't import emails or contacts without downloading a Outlook Assistant hotfix from Microsoft. 4). Dell said they did not have drivers to support the AIO 962 printer, however they offered another AIO printer for $149.00. 5.) All in all if that was the worst of it, I'm happy. I've been doing microsoft upgrades since the days of DOS 2.0, so we have came a long way.