Definitely second getting an SSD instead. It's the single biggest upgrade you can do to a PC today, especially for laptops. If you can live with 128gb of storage, a RealSSD C300, the current performance king (although check Anandtech for updates, this is changing all the time) is $264 from Newegg:
I would actually give the SandForce drives a try. They have better garbage collection. TRIM is coming in Snow Leopard, but it is always nice to have good garbage collection on the hardware.
SandForce wins right now in $/gb, and 4K writes. It loses in anything that is limited by the SATA2 bus, such as sequential transfers.
The stories about TRIM coming in Lion also pointed out that so far it was only supported on Apple's own SSDs.
Also, the major problem with Sandforce drives on Macs is that their firmware can only be updated a) under Windows, in Boot Camp, and b) with an MBR-formatted disk. That is bullshit.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148...
This thing will do 30,000 4k writes a second, which is orders of magnitude more than a 2.5" mechanical.