Just make sure your BIOS will work with it. Most motherboards these days have updated BIOS's to detect dual-core processors.
I also agree with BigLu. Even when Core 2 Duo releases and AMD does the price drop, the cheapest Conroe based processor will be the E6300 (1.86GHz/1066MHz FSB & 2MB L2 Cache) costing $206. That's only about $50 from the projected price of the X2 3800+'s price after price drops, yet it'll perform way better than the 3800+.
If you ask me, the best Core 2 Duo for the price and performance is the E6600. Running at 2.40GHz with a 1066MHz FSB and 4MB L2 Cache, it will only set you back $316.
Don't forget that the Core 2 Duo processors overclock wonders. Just air cooling is sufficient enough to get it to 3.0ghz, and it won't be like the Prescott and become a stovetop, thanks to it's 65W TDP.
Oh and did I mention that the E6600 is already good enough to compete with the Athlon FX-60 just by stock speeds? This isn't even the highest variant with the E6700 and Extreme X6800 above it. Keep your eyes peeled once July 23 comes around.