Need help/advice to upgrade older HTPC

Hey guys need a bit of quick (easy, I hope) help.

I built a 'cheap' HTPC about 3 yrs ago, that really was used as more of a TV connected PC for surfing the net from the couch. I didn't get an OTA tuner at the time because their wasn't many good ones out. I didn't get a great video card, but was told what I got should be good enough once I got the OTA tuner. I bought an OTA tuner cheap at a Going out of business Circuit City, and it didn't seem to work the greatest, choppy video and can't get recordings to work easily.

I think I need to upgrade some components to get it working better.

Here is what I have:
MOBO Abit KN9 Ultra
CPU AMD Athlon 64 3500+ single core
Video Gigabyte GeForce 7300LE
RAM 1 Gig OCZ Gold DDR2 800
Tuner Pinnacle PCTV 800i

I am looking for the cheapest, yet still good, way to get this system to act as a 2 tuner PVR for OTA. Currently unemployed and figure I need to cut back on some things, so I am gonna ditch Directv and just watch OTA. Hoping I can do the upgrade for just over 1 months bill (about $100)

Open to anything, more RAM, new CPU, new Vid Card.... and of course at least 1 more OTA tuner.