I've been keeping my eye on the SSD market, there is a good comparison tool at AnandTech site AnandTech SSD Bench - View CPU Bench
, you can select two and view his results side by side or a single bench for all listed SSDs.
The most important benches to look at are the I/O numbers and the random read/write.
His Desktop IOMeter 4k Random Read scores
are interesting, this will have the largest effect on performance.
The AS SSD score, don't know how much stock to put in this as haven't found how it's derived, always seems to favor the Intel SSDs.
As far as size goes, I've got the X25 V 40GB, with 23.8 GB free. Depends on your software loading. YMMV.
I'm checking on a claim that System Restore interferes with Trim functioning correctly, so turned mine off to get a comparison.
The controller on this little Intel has horrible write numbers, but gets good reviews and overall good scores.
The OCZ Vertex 2 50GB has some very good numbers and highly rated on several reviews and is in my top two list.
Look at AS SSD and CrystalDisk benches for this and compare to others. Of coarse, taking into consideration that small deviancies can occur from setup decisions.
Happy researching, and let us know the outcome