|There are a lot of components to game play. To start you really don't have enough ram in my opinion. I think 1 gig is minimum and 4 is great.|
You don't say what video card or how much memory it has. This is also very important information concerning lags.
There is also the issue of system resources. Review what your are loading on system startup. A lot of things get installed by default that don't need to be in your startup. Printer monitoring, chat programs, etc are just consuming resources when not being used.
Since games write temp files you need to think about your hard drive. When was the last time you ran disk cleanup and defragged the drive?
Then there is your internet connection.
Just as defragging your drive can make a huge boost to game play, being virus, bot, trojan, spy/malware free is even more important.
They can rob your bandwidth.
Next step would be to do a tracert to a game server you have great performance on and compare it to one from the problem site.
At a cmd prompt type tracert ipaddress
or tracert hostname [game server dot com]
Post those results for review.
Next do a bandwidth test [dslreports.com, speedtest.com]
Post those results.