I've got experience with both actually. I liked Monarch right up until they wouldn't give me money back on a bad motherboard. They received it, said it was all set to go, then just didn't do it. Finally several weeks later they gave me the credit. I've ordered from them several times, and so have some friends, and that's the only strike against them. Also of note - they are slow. I think they take your order and then source the part perhaps? It ALWAYS takes several days to ship something. If they have the lowest price, you will get the part, I trust them on that, it just won't be very quickly.
NewEgg has ben nothing but perfect for me. I think they are my favorite computer store. Everything always comes sooner than I expect it. I also dig how you can see right away if they have stock on something. In fact, I've never heard anything bad about them. I got my GF3ti200 from them in fact, a month ago or so. Just bought a HItachi monitor from them on Sunday, and have had it several days now - this was ground shipping - it was like 3 days to get it.
I'd recommend Newegg, even if you have to wait. They have something where you can give your email address and receive an automated e-mail when stock is on hand again. I'd do that, and just be ready when you get the mail to place an order quick.
