limits

Ok, i just bought a dual channel 512mb (pc3200) ddr set, before i bought this my comp ran smoothly, so i installed it and i was getting lots of harddrive lag playing games and running programs (you can hear the hd grinding now and computer skips) i checked bios and had to change my ram settings to pc2700 because my processor's fsb is 333mhz and it still skips so i tried installing old ram to see if this was the problem, still no luck. any suggestions? System specs: Athlon XP 2800+ (fsb 333) A7n8x Asus Deluxe mobo 512mb pc3200 dual channel ddr 3 hd's: SATA 150 160gb ATA133 60gb (windows installed) and ATA 100 15gb Video card: Gainward Geforce 3 (ti220)

Well im on windows xp pro, i have the ata133 drive on master, the other 15gb is basically not used for the sata has all my backups on it (70 or so gigs worth) .. plus i couldnt figure out how to install windows on the sata because 1)Its not on the windows install screen and 2)It only reads 32gb on fdisk for partitions.. it only shows up in windows when i install the drivers for sata. and yea i tried defragging the drive before.. helped a little but it doesnt seem like this would be a buildup related problem because it had just been working fine, i was thinking you had to format when you installed new ram? but i dunno..