yes 3200 is better.
According to the manufacturers website...
1. Type: Dual channel DDR400/ 333/ 266 -184pin
2. Max capacity: Up to 4GB by 4 DIMM slots
Your using 1 stick of the fastest memory your motherboard can support. So to max out your memory you can have either 4 x 1gb, or 2 x 2gb sticks of DDR400 (pc3200). Of course having just 2 sticks would mean you will have 2 memory slots open but your motherboard can only support up to 4gb anyways. If your only have a 32 bit operating system you can only use around 3.25 gb anyways, or somewhere around there, I know a 32 bit operating system cant use 4gb. If you do buy more memory and plan on also using the memory you have then either try to get the exact same memory that your using or memory that has the same specifications. If your motherboard only supports a maximum of DDR 400 then its probably time to upgrade, not that DDR 400 is bad but there is much better out there.