Anything i can do to increase performance

[winngames]

seeing that im using a dell theres no chance of overclocking, is there any upgrades that would be worth investing in to increase performance, im looking to spend no more than £300

 

[winngames]

yeah its a dell, i have the xps 720. ive tried overclocking the cpu using ntune the highest i can get it too is 2.6ghz, should i just wait until the extreme processors go down in price

 

[winngames]

. At times it would be nice to have a non-overclockable PC that would be pretty much bullet proof

lol have you seen the dell xps 720, it is practically bullet proof solid metal case and weighs just under 6 stone ^^, btw would sli 8800gtx be a good option seeing that theres not much i can do