the same as nick, www.ebuyer.co.uk VERY fast service, massive range of products and customer service is great.
recently had a problem with casetech.co.uk i ordered a molex > sata adaptor because ebuyer were out of stock on them. i payed for next day delivery so i could use my new SATA drive and it didnt turn up. so i waited one more day, still no adaptor. went to the "live suppport" section on the website and got to talk to some guy who said they would send another out. so 5 days later i still had no adaptor.
so i went back to "live support" and was firm with them this time telling them my business has been without a couputer because of them and they bassically ignored what i said and told me that the adaptor was out of stock and wouldnt give me a refund so id have to wait. about a month after i ordered it i get a package at the door, and it was the adaptor. i had already bought one else where though!
I usually search New Egg just to see what is available at a good price. I can seldome find a similar price on any item locally. Finding a specific quality product in a local store is also very difficult.