need the best OC potential/ price cpu and mobo

so here's the deal....i've got a really old socket A K7 sempron with a year old mobo but nothing fancy. i really need to upgrade now but don't want to get the new AM2 or Conroe until things have been tested and bugs worked out. so what i'm looking for in the mean time is the best cpu/mobo combo for oc'ing for the cheapest. i don't plan on using any special cooling , but do have a nicer cpu fan, and 3 case fans. My only reqs. are that the mobo be able to accept ddr2-800, pci-e for a 7900gtx, and that's about it. so let me know what your ideas are. even tho i am partial to amd im just looking for dirt cheap ocing performance.

oh, and i'm looking to spend no more than 300 on the combo and im only ocing the cpu not the memory or video card. i will be playing BF2 & DDO mainly on this.

thanks
Chris

this is what i currently am running:
all info from cpu-z (sorry can't get a screenshot)
AMD Sempron Thoroughbred 2500+ Socket A @ 2.1 Ghz
Mainboard AsusTek A7V600-X Chipset KT600
Memory 512MB PC2700 (don't remember maker) 2.5-3-3-7
Nvidia FX5500
WD 40 gb 7200rpm SATA
Seagate 20gb 5400 SATA

currently, i'm sure there are no socket 939's that support ddr2 so you're limited to intel platforms. i have no experience overclocking with those so i won't even try to post something on them. Although, i could reccomend you use an Asrock 939Dual-eSATA2 mobo ($46 refurb @ newegg or $72 retail) with your current ram and vidcard but have it running an Opteron 146 which can be bought at monarch computers for about $149 shipped with a coupon listed here.
Those little pretties overclock like beasts (i've heard they are able to go 3.0ghz+). Although you won't be getting the top performance you can have with pc2700 ram, you can still get a very nice cpu overclock. i have 768mb of ram runnin at 133mhz with opty 165 CPU @ 2.6GHz 1.3 volts, can go higher but i didnt want to do the voltmod yet. Fairly cheap setup with room to expand later if you wanted.