will this help me any, do you think i will see a boost in performance
What OS are you using? Provide full PC specifications including detailed specifications on all of the RAM modules, your CPU and motherboard.
If the 256MB module won't run at the frequency of your other RAM, you'll increase the capacity and decrease the throughput.
If you're presently running Dual Channel with your RAM, you will effectively disable that by installing the 256MB module as far as I'm aware, so that's something to consider as well.
look down VVVVV, i know the ram will work with the system
Nope, don't believe that little increase in RAM will make any noticable difference. Perhaps in some benchmarks you'll see an improvement, but I doubt you will 'feel' it.
based on your processor - an Athlon XP 2800+ - no - you will not see any increase in performance.