i personally am going for an HD3870/50, with the E2140, cos i need to finance an OS and monitor... i would suggest you try and shift yor budget to fit in a Wolfdale processor, IE, the 8400... cos the AMD processors atm aren't really worth it, 'less you want to get a phenom, IMO
I would stay away from generic memory. It can cause a lot of errors which are hard to detect. Since you are on a budget, I would get Kingston. Other good brands are Patriot, Corsair, Crucial, OCZ. Take a look at the venor's qualified memory list on the Gigabyte site for your motherboard.
5000+ Black processor...? I don't want something too weak. Ideally want a processor that can encode/resize a 120min video in 120 mins or as close as possible. I don't know much about processors in that respect. I just picked AMD cpu because they are cheap and the 5600+ was the cheapest one with 2MB L2 cache.