The industrial strength SSDs have 2x the space they report so they can do some tricks to speed things up.
As near as I can tell, the Intel X25 drives are as good as they get, and it may be the ultimate thing to add to your system to get performance.
Speaking of performance, I figured out a nifty trick today. Ubuntu has a ramdisk sort of feature built in, /dev/shm. You can copy files to it like it was a hard drive, but they actually exist in RAM. On a not-so-fast PC I use at work, I copied a 350M file to /dev/shm in 8 seconds the first time and .5 seconds each successive time. Linux cached the file on the first read in unused RAM as a disk cache, so the successive copies were cache to RAM disk. The tempfs ram disk in linux expands as you write to it, so it doesn't take anything until you use it, and if your system needs memory to run apps, the tempfs files are written to swap. Ideal.
So I found you can point your firefox browser cache at /dev/shm. Type about:config in the address bar and then find or add a string key of browser.cache.disk.parent_directory and set it to /dev/shm. I did this and sure enough, a Cache/ folder appeared in /dev/shm after restarting firefox and it flies.
http://apple.com took 2.5 seconds to load for me the 1st time, and out of RAM cache, it loads in .7 seconds.
I found a ramdisk for free download for XP using google and installed it as R: (a 30M size is enough). Did the same trick, and it makes windows fly too.
So I'm thinking of making heavy use of /dev/shm if I get an SSD. Put my log files and /tmp there so the SSD isn't so busy writing little things all the time.
The downside is those things go away if you don't periodically copy them back to the SSD. For browser cache, who cares? For log files, you probably do care, but it's less wear on the drive to do a copy once per half hour than to do all those little writes...
