In my case I had no problems when I last used them, but like you I've heard a few horror stories about them. I'd have to think hard about using them again.

My favourite online suppliers are:

www.overclockers.co.uk

www.komplett.co.uk

www.dabs.com

I've also heard good things about these 2 but I haven't tried them yet:

www.simply.co.uk

www.scan.co.uk