If you went with the E5300/P43, then you would also need to get a graphics card. AMD actually offers better price/performance and a better upgrade path in the low-end. I don't see any reason at all to use Core 2 on a new build. I wouldn't use 2GB of RAM with a new build either, especially with a 64-bit OS. These components added to the rest of build's system only raise the price by $37 and give you a slightly faster CPU and 4GB of DDR3 RAM while staying under budget.
I actually just copy and pasted that build from a different thread I posted in a while back which had a smaller budget, that's why it only includes 2GB of DDR2 RAM. I agree with shortstuff with regards to AMD over Intel for budget builds and the upgrades he suggested is definitely worth considering.