you shouldn't have an issue running that card you ordered as far as compatibility goes. you would just have to make sure your motherboard has a x16 slot, which it does, so it should run without issues.
if you were to get this board, the minimum you would need to replace is your cpu (since it's a different socket), ram (since it requires ddr3), and case (since your current case only supports m-atx boards).
things that you could reuse;
that board, like many modern boards now, only supports 2 ide (pata) drives. i know in a previous post, you mentioned you have 2 hdd's and an optical drive, being 3 total, so you're gonna have a problem if they're all ide. if they're sata drives then you'll be good.
your psu (maybe). from what i can find i think your current pc only has a 305w psu. if you really just could not afford a new psu, you might be able reuse it, but personally, i wouldn't risk using that crap to run some brand new parts.
and your gfx card, whether you use the one that came with your pc or the new one you bought, they're both pci-e x16 so either would work.