Asus PN5-E SLI and slow performance

[themadmonk]

PN5-E sli mobo 650 sli chipset, E6600, 2x1gb crucial ddr2-5300 ram, evga 8800 gtx 320 superclocked, 2x250gb sata2 seagate drives in raid0 and 1 seagate 500gb backup, thermaltake 700 modular psu, 2xdvdrw's floppy and card reader running windows XP + sp2


right guys and gals, my problem is one of slow performance in everyday tasks which i dont think i should have with this pc, for example if i've minimized my browser to do some other tasks and then i return to it, it can take about 8-10 seconds to fully open so i can use it, usually it shows an outline and then fills the rest of the screen. sometimes when i goto windows explorer im greeted by the little torch looking for things instead of showing my drives etc
i have the latest nvidia drivers installed, i used F6 during xp install to use sata drivers from the floppy that came with the mobo, i have all the latest updates yet i have this slow pc.
it appears to test ok, seagate tools reports no issues and games play fast, it seems to be when i switch from one task to another that i have this slowdown and i really think its a driver issue rather than a hardware fault as 3dmark reports over 9k which is good for this system. its as if it puts all its thought into one proggie and doesn't like change

any ideas what might cause this or things i can check/test???

i have posted this on another site so sorry if any of you guys have already read this