it's been my experience that an SSD is not that great as an O/S drive unless you raid them. If you use it to hold as just WoW it should be fine.

I have 4 on a caching raid controller as raid-0 and the machine smokes. Have the O/S and WoW both.
When I tried just one drive as an O/S drive I got small 1-2 second lock ups during use. SSD is wonderful if you're mostly reading the drive. When it's your O/S drive you end up writing to the pagefile all the time and for some reason you get blazing speed and then as if the cache is full the drive takes a second to clear it's buffer or something. I never liked SSD on my laptop, I couldn't stand the lockups.