ya, what he said, look at the manual for it, normally they go in the same colored slot, i.e. my motherboard is an epox ep-8rda3+, to use dual channel, you have to put it into the two green slots.
from your manual, it looks liek you should put them into the first and 3rd slot..
AMD Athlon XP 2800+
Thermaltake Big Typhoon
Epox EP-8RDA3+ rev. 1.1
Corsair XMS 2x512mb PC3200 C2PT
ATI Radeon 9600 Pro 256mb
Maxtor Diamond Max 9 80GB SATA HD
Maxtor Diamond Max 10 80GB SATA HD
Lite-on 16x DVD/48x CD-rom drive
Lite-on 52x/32x/52x CD-RW Drive
Creative SB Live! 5.1 Digital
Antec SX1040BII Case
4x80mm case fans, 2 in, 2 out
OS: Windows XP Pro v.SP2