Phenomenal! It almost doubled my PCMark05 HDD test score from 4.9K to 8.8K, and boosted my overall PCMark05 from 6.2K to 10.6K. This with a hard drive upgrade only! Who knew? I've always looked at HDDs as merely for storage, but the OS and all your programs must be read from it, and all your saves must be written to it. It's the second most overlooked aspect of a PC, behind the Power Supply. Well, i'm silly satisfied, and if you can swallow the price in an age of super cheap storage, it's well worth the investment(and the windows re-install).