i wouldn't personally buy an NZXT lexa case at all, what other cases has your friend had? has he had experience with some of the better case manufacturers out there?
if you're looking to do water cooling and it's a first time may i suggest a thermaltake LCS case? the come with all the bits necessary including coolant to make a 120.2 or 120.3 CPU loop, all you would need to do is buy a GPU cooler and you'd be set. additionally it's all internal, and you wont ned to do any modding.
if however you are keen to do modding then the lian li series is a very popular series for water cooling, there are many fine examples on this site, including raikiris v1200+ in black with a custom side panel window.
if you have any other questions feel free to fire away