WildFire
Warrior of Linux
Keep in mind that the actual encoding/decoding/rendering processes in video editing software are more dependant on CPU power than graphic adapter.
In gameplay use the graphic adapter makes more noticetable difference.
4 GB is the upper limit 32-bit operating systems can utilize, maybe that's why you're aiming for 4 GB?
But you do have OS installation disks already? Buying a new OS easily costs around 100 - 160 € (not sure how much that is in pounds).
As a sidenote you shouldn't ignore hard-disk either, if you're planning on doing video editing you'll need loads of HD space (for me, recording 25 minute long Legions round with 1680 x 1050 resolution takes about 85 GBs).
I know that


Yarr, just seems the right number to me!
My sister goes to university so I can probably get windows 7 for free (and have done, as my sucky computer is running windows 7 professional 32-bit. I'll see if she can wing a 64-bit though. I wouldn't mind dual booting it with ubuntu either.
Sorry for the late reply as well!