Which store has best download quality?

I have never downloaded music from a store before, but there's an album i've been looking for for years which has just surfaced as a digital-only purchase (it never made it to CD!)

I usually buy or borrow cd's, load them on the pc, then download onto a zen for my girlfriend, and for me i am happy with using a traditional cd to minidisc set-up for mobile music (until i get my own dmp, which will hopefully be a trekstor vibez when pennies allow..)

I want to buy the best quality format, and looking around, have found that the album isn't available on the new itunes plus drm-free super--duper bit-rate format, so are all the others the same? (virgin, tesco etc?) are there any lossless legal sites with huge catalogues? i suppose really i want the cd, but it don't exist, so just want best version i can get! thanks for any advice or info, Johnny.