Sony DVD RW Problem !!!

I just got myself a pc last week which i have stated in quite soem posts now ..
just for the help the config is
E6750
DG33FBC
250GB SATA
2X1GB RAM
Sony NEC Optiarc AD-7190A 20x DVD±RW IDE Drive (Black)
also i m using 7300GS card..
but whenever i am copying anything from DVD or using the DVD in my writer,my machine slows down a bit ..actually not just a bit but considerably
mouse will move with jittery motion ...
games will get slow..
performance will be terrible..
Anyone who can say why is it so??

For any info on the DVD drive:
*www.geeks.com/details.asp?invtid=BLK-AD-7190A&cat=DVD