I've got an AM2 socket AMD X2 5000+ sitting around (somewhere) if you wanted to do a cheap upgrade. It's enough power to handle blu-ray decoding also (even with onboard video if you go with the ATI HD 4xxx series) if you ever wanted to go that route (I don't think your existing setup would do that, the 4800+ was the minimum CPU for blu-ray capability during the testing at the time anyhow...).
But it would involve you getting a new board/ram possibly (but that would itself fix your video problems with onboard graphics). If you want it, just let me know your address. And let me double-check to make sure I still have it before purchasing anything. I also have a few of the OEM coolers I can throw in (from hotter chips than that too, so a bit of an upgrade there... sort-of...).
Anyhow, if you're interested, let me know. PM me your mailing address and I'll dig it out of my spare parts room. It'll be shipped UPS or USPS, in OEM style packaging to protect the chip (static foam and plastic). The chip is a known good chip (but as we all know, shipping can always cause the unexpected) as it leaves my house and was my HTPC chip for not quite a year before it was retired. Never overclocked, abused, etc. I'd still be using it if I didn't get a hotter AM2+ Phenom II from another retired system.
Ohh, and no charge if you were wondering... If it works out for ya, reimburse me for the shipping after it's running if ya like.
Anyhow, you could get a board and 2-4G of ram for ~ $100 or even less if you go budget lineup. Anyhow, it's just an option you have. If you want it, just let me know. If not, that's fine too. But it would also open up the option for PCI-e video if you wanted to go even further down the road.