Computer slows down. Like..really slows down

If i burn anything my pc slows down. Not to a crawl...i guess about half-speed. This applies to everything: I can't play videos or listen to music when i am burning, the rapidshare timer ticks down half as fast, even my typing buffer thing seems to be slower. Task man says it's not eating all my memory or cpu (which is a dualcore riding 1GB of corsair)
Sony DL 16x

It wasn't always like this. Formatting would be a real hassle. Do i need to?

ty

uh
my computer right click > properties > hardware > device manager > + IDE ATA/ATAPI controllers

Primary and Secondary ide channels is what you want to check
double click both and check advanced settings. Should say DMA if available in all of the enabled dropdown menus, and typically Ultra DMA Mode 6 (or a smaller number) on the "Current Transfer Mode" box

If that all checks out, then DMA is enabled and supposed to be working and something else is fucked up.