From XP to Vista and back to Xp

[apparas]

I have a Sony SZ3XP/c which came with Win XP.
Sony has sent me the Vista Business DVDs in order to upgrade the laptop. Everything wentwell with the upgrade and I was working about 6 months until i bought a 4GB flash memory.
The USB did not recognize it and then any USB device could't work..(mouse, flash memory...it asked software in order to install it).

In a forum I discover that is a Vista problem...So I had to return again to XP...Any similar problems?
Apostolos