I saw this offer the other day in my local store, i was tempted, until I saw that it was a g3 :-( I have a g4 tower at home already and that in itself is as slow as a dog. Even the low rated G5 that we have at work is not that much faster than the G4 dual I am using. IMO get a cheap PC laptop for about £300 that is really all this offer is worth. After using macs for around 10 years they are no way near as fast for the money as PC's. I use a sony 400mhz for net and email with WLAN to my office. Cheap and faster than the mac.
For the love of god noooooooooooooooo!
To make this worse you have to deal with the after sales at PC World which is seriously lacking, you have been warned!