What kind of problems are you experiencing?
But just looking at your specs, you are memory starved. 1.5gb is the minimum ram requirement. You also have to take into account ~2gb for your OS, and that just leaves .5gb for whatever else is running.
Bump it up to 8gb - either buy a new 2 x 4gb kit(safer), or another 4gb stick with the same speed and timings as your current one.