Thanks both of you, seen an S3 for £340 inc p&p (Ebay), good deal?

Hi all, looking at setting up a mining rig asap and just need a couple of pointers to stop me wandering around for too long looking lost 

Firstly, where should I go to figure out what hash rate I'd need to turn a profit (for the record, I don't pay for electric), and secondly, where should I look to figure out what ASIC I should purchase (comparison maybe?), or if anyone can make a recommendation, I currently have £100 and can add £40 a week to that...

Thanks in advance.