You might want to try an optimizer, I personally have a crappy desktop (looking to upgrade in next while) but a couple of months ago I found AMD fusion, basically it's a program you launch and there are various setting that will help increase performance. I use it every time I game. There are multiple default profiles that disable unwanted or unused services. In wow I run about 15 Fps in dalaran once AMD fusion is on I run about 35 fps which is a big increase. There are some options that will run your hardware harder, but they can also be disabled.
Amd fusion can be downloaded from...http://sites.amd.com/us/game/downloads/fusion-for-desktops/Pages/overview.aspx
There is also a forum you can look to if you’re having any problems with it. It’s a very useful tool I recommend to anyone with a subpar machine such as myself >.<