Will UT3 work for this spec?

[re8]

will this play it

Dimension 2400 single core 2.66 ghz
789 ram, dont know the graphics thing but chip is Intel Extreme graphics controller 128 mb

You'll need a real graphic card. Watch for the demo's results in a few days to find one that works will with UT3 & you can afford.
But, it will still be low-res for you, due to the single core. Would help if you had the CPU name, etc.
http://www.cpuid.com/

[Flak]

The demo is coming soon and you'll be able to check. Closing, there are enough threads like this.