4th time lucky!
Have AMD chip. First attempt to instal SP3 locked up and had to be backed out. Next 2 attempts backed themselves out (although one required a system restore to stop the PC freezing up). 4th time worked ok.
Guess I'll have to instal the patches for my family as it doesn't seem very friendly.
Think I'll go for a Mac when my hardware reaches end of life. I hear they are less hassle!...