Ram wise, I guess you could see some performance gains with 2gigs... but more in the form of load times, if you had some stuttering in games then it might help. But I have to say I have 512 on a budget gaming machine and it runs fine. As for 512x4 or 1x2, the less the number of sticks the better, for performance and upgrading wise.
As for OC'ing software... I don't think universal cpu overclocking software exists, let alone a fesible idea.
Is you computer a prebuild, like a Dell, compaq, or soemthing else? If it is, you really can't do much other than upgrade the parts you can (which is more or less futile for your setup) or build a new one from strach.
If your current comps not getting the performance you think it should, clean it up, start with only the OS and drivers and must have software. Use programs like firefox and be careful.
But then again don't expect performance you shouldn't be getting.