The first rule of thumb before daring to try something new is to back up you hdd, Ive been where you are right now and its not nice, i read about the problems of downgrading from vista to xp before I upgraded so took the necessary precautions, partitioned my hdd and stored a ghost image of xp on that. so when like you, I had problems mainly with software I just restored my xp back from my xp image on the partition. in less than 10 Min's.
Since then i have set this up on friends computers as they where so impressed by its efficiency
Compaq Presario CQ5305K-m Intel® Pentium® Dual Core E5300 (2.6 GHz), Windows® 7 Home Premium 64 bit, 2048 MB , Hard drive: 320 Gb, with 18.5 Widescreen
SPURS TILL I DIE (DIAMONDS ARE FOREVER SO ARE SPURS)
TO DARE IS TO DO