Actually I would suggest that since you are not really into tweaking the clock speed etc, why not save up a little and get intel's motherboard. it's super stable and cheaper.
By the way, Fuwell is not necessarily the cheapest store in Sim Lim.. What I did was that I walk around to shops and ask them to offer me a spec that best suit my usage, and they will advise your accordingly. In the end I got myself a quadcore 2.0GB system, with intel motherboard, 2 GB ram, and GE8800 GT for $700 I think. I got my own XP pro so I safe on that. It's a good bargain even till now. At different time, different shops might have their own promotion. Just listen to what they have to offer, and get out of the shop and think about it.. or go other shop and ask for quotation again.
I din't really read all the post in this thread, but in case no one answer.. actually if you know how to take out your harddisk and bring it to Sim Lim, they will put your hard drive either as your secondary (slave) drive, or u might not need to get another hard disk as welll.. just reuse the hard disk and reinstall the drivers for your motherboard and other devices, Your new pc will be up and running.. This way, u can safe up on your Win XP professional as well. Also, u might wanna look into using back your DVD/CD drive. Just a thought from me.. =)