I have a friend who had a Mac 5300 and it was plugged with a PowerPC chip (120 mHz).
So yours should be a bit faster...
Try
http://www.apple.com :-) for more information...
About the £50... What's it worth to you? All depending on your needs you should consider what you are going to use it for... It's as you probably know, brilliant at smaller graphic-works...
