Yes, 32 bit xp supports ddr3. It will not be able to see all 4 gigs. though. Likely only ~ 3gigs. You will have to upgrade to a 64 bit os to recognize more than that. This issue is not operating system related.
Are you trying to run the ddr2 and ddr3 sticks at the same time? Don't think that will work well. Also, you listed two different part numbers for ddr3 ram. Do you have platinum or xms3 or both?
You may need to flash bios to get this board working properly. Do not do within windows. If you decide to do this please feel free to ask for walkthrough.
Latest version 2103:
http://www.asus.com/Product.aspx?P_ID=ShiLE9XNeuFKwFDC
The psu listed is not enough to power your system. You need to be up here:
http://www.newegg.com/Product/Produc...=corsair%20650
Probably not the cause of this problem, but will need to be addressed.