I have been trying Windows 7 since it came out in beta, I installed it in a 32bit Dell GX270 desktop and a 64 bit Toshiba Tecra A6, and it worked OK, specially in the 64 bit machine, BUT, in this machine after I installed some programs and booted the machine some programs disappeared, at first, not having a very structured mind I thought that I have not done so, but after doing it for the second or third time, it was obvious that the programs disappeared. Directories where there, and a lot of files, except for the exe files. I look for a lot of solutions in the Internet but, as always none made sense, or did not worked. I changed Avast and Kaspersky for Norton Anti-virus but nothing seemed to worked.
I removed System Restore from my system. I do like the idea of system restore, I have seen it work with a friend of mine, after he installed some software, but for some reason, unknown to me, system restore was deleting the software I have installed. Very weird solution, but at the end it made sense.