Well ... for starters, it's SATA-II,
not SATA 2 (no I'm not nit picking, it's because the II is actually part of the acronym), and just because a drive is listed as SATA-II doesn't mean it's capable of 3.0Gbps. It's a long story and a numbers game, but to be safe, stick with drives that identify themselves specifically as 3.0Gbps.
One of the numbers games I'm referring to is, as in your case ... ATA133 v SATA II 300 ... is 133 faster than 300
There is a lot more to it than my simple analogy ... suffice to say, go get another SATA-II / 3.0Gbps drive as a replacement, SATA-II 300 does wonders for multimedia and content creation. The higher transfer rates help in audio/video data throughput more than in office productivity applications due to the requirements for large amounts of data to be moved.
... who's to choose? one is as good or as bad as the other, personal choice is left to you.