I love Gigaparts. I've never had a bad experience. And on the rare occasion when I've asked a question their sales guys didn't know, they didn't flounder around or lie; they found me someone in the building who did know and could explain it well. (Even their bathroom makes me feel like I'm in a high-end electronics store, with a poster on its wall of the full electromagnetic spectrum).
Pros: Highest quality parts, internet prices, knowledgeable staff
Cons: A little out-of-the-way, under-staffed when busy
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