Pros: Memory worked great with no problems at all. I installed 4GB into an XP-Pro machine that I built.

Cons: I wasn't happy with the price doubling (I can understand modest increases, but doubling becomes cost prohibitive). I came back to order more (since I now have Windows 7) to go to 8GB, but don't want to pay twice as much for the RAM.

Overall Review: I was going to go up to 8GB on this machine and do the same on another machine (by replacing the existing memory) - that would be $300 now. For $150, I would have gladly paid it. For now, it's a lost sale.