Chris
it really depends on what is important,speed of processing,graphics capability,storage etc
Also it would make sense to get a stable operating system like XP.
Things to think about, do you need wireless,bluetooth,cd/dvd writter
you really need to get an idea on what it will be used for and then look online for reviews.
Processor speed is one main thing that costs,Dual core is the way to go, but not sure you will for £300, you will find that £350 gets you a far better lap top than £300, i found that out when Niki got hers.