I'd go for the velociraptor (actually, I did go for the velociraptor - I have a pair of the 300GB models in RAID), but that's mainly because I couldn't live with just 64GB of primary storage. I use far more space than that, even just for apps and such.
If you have massive amounts of storage in separate drives there's no reason not to go with the SSD's.
Except that if you want your programs to be fast, rather than just your OS, you need enough space on your fast drive for both your OS and your programs. Unless you only have a few games, 64GB is probably not sufficient. My fast drive (554 binary GB total) has 260GB free for example. I use a lot more total storage than that though - I also have a WD 1TB data drive that has over 500GB used.
My understanding is that the HDD speed affects the loading time of the OS and apps more than the actually running speed...
Based on that I'd either go for a performance SATA (WD caviar black for example), or if the speed is that important go for the SSD drives.
A normal install of Vista can take up to 15GB, XP isn't too far behind - so that would leave around 50GB for games and apps (if going for SSD). So that part depends how much extra you want to install on the faster drive - if you're happy with Office taking a couple of extra seconds to load up that can easily be put on another drive.
Last note is that the raptors have a reputation to be more than a little noisy, and tend to slow down a lot when they start getting full - so while you may have a total of 300GB available in that setup, if you want the performance only 1/2 to 2/3 of that would be 'usable'.
When I built my pc up (all of three months ago) I went through similar problems and this is pretty much the advice I got given then. I ended up going for the caviar black solution due to money, but fully intend to get SSD drive(s) some point soon.
I went for the SSD option (but addmitedely 2 x 64GB) and didnt have a problem with the amount of apps and games (I rarely have more than 3 games installed at a time anyway) and am VERY glad I did.
The snappyness of the system and load times (I can get from login to ingame with all textures loaded etc in WoW in under 6 seconds, even with all my addons) are instantly noticable and other machine seem sluggish in comparison.
Remember if you have 4GB of RAM you should be able to switch of your page file in windows, this will save some space.
Also I switched anything that didnt need snappy load times onto my 1Tb storage drive, this included all the "My Documents" type folders (music, pictures), everything except "My Desktop" and then on the desktop I ONLY have shortcuts, no actual physical files. This helps with space and reduces read/writes to the SSD's. You can do this (and I would recommend) with your Internet Explorer (or similar) temporary files also.
Go for the SSD's for your system drive, quiet and supremely snappy, you know you want to ;-P
Note that Velociraptors have changed the trend of Raptors being noisy. I can't hear my Velociraptors at all under most operation, and even at their noisiest, they are quieter together than my single Caviar Black 1TB drive.
Oh, and I know what you mean as far as noticing the system responsiveness. It's noticeable with my Velociraptors vs a standard setup, so it would probably be even more so with a good SSD.