1. microsoft anti spy beta 1 (find it on the microsoft.com homepage)
2. spybot search and destory (google it, free download.)
3. lavasoft adaware (google it, also free home/personal edition)
download and install all of these. restart, boot into safe mode, and run full/deep scans with all three of those tools (in that order) and you should be cruising again.
fyi - firefox's glory days of fending of spyware have since ended. always run ms antispy, and do regular scans with the other two. you do have anti virus installed, right? and you do update your definitions daily, right?
that's our corporate IT policy and works for us....usually.
sweet dreams
edit: for your registry woes, try tweak now reg cleaner. the say it's free, but i've never used it.