I use a product called SpySweeper that informs me when such actions are about to take place and gives me the option to leave my homepage unchanged. It works for me.
I have Spy Sweeper too, it also finds it and deletes it, but it returns
"I use a product called SpySweeper "
Well I downloaded the trial version into Windows 2000 and it
screwed up my system even after I had removed it. Basically it trashed my login directory so my desktop disappeared.
They claim the problem exists in the trial version but they lost me at that point. I sure was not going to pay to find out.
I use Spybot and SecureClean, seems to get about everything.