IMac :: 3-5 Second Response Delay Of Mouse Or Cursor?

This Imac 7.1 2ghz, 20" is less than a year old. I switched because it promised friendlier functioning especially for my wife. I use Parallels for XP/Quicken only. What drives me crazy is a 2-5 second delay for almost anything I do: scroll, copy, move cursor, any art or photo ops and TYPing. I read all the things to reduce the Pinwheel and did them. Finally I added 2 more Gigs of memory (total 4) and it made no difference. Activity monitor shows tons of free memory.

I cannot believe that I use my tiny Asus to type most of my stuff now because on the iMac I can type something then in the middle of a word, count 'one thousand 1-3 then sometimes get a pinwheel for 2 counts and it resumes typing. It does not seem to matter much if I close everything else (wow that eliminates all that handy windows stuff Apple is famous for).