Should I keep my OS on this drive?

I currently have Win 7 64 running on a (Refurbished) WD VelociRaptor WD740HLFS 74GB SATA 3.0Gb/s.

Obviously all my user files and settings are on this drive. I try to keep it as clean and light as possible. (I have a dedicated file server on which I keep anything that isn't a program.)

I keep all my programs (ok, mostly games) on a WD Caviar Black WD6402AAEX 640GB SATA 6.0Gb/s

My question to all of you is: Does it makes sense to keep this as my config, or should I dump the Raptor and put the OS onto the WD Black?

I *am* saving up for (a wedding, so I haven't bought it yet) an SSD so that is ultimately where I will end up, but it's going to be awhile before I shall acquire it. I don't mind putting in the work to move the OS over to the other drive, but I just want to know if I will realize any *noticeable* performance gains (OS boot time, game level loading times, application "snappiness") by doing so. I know the WD Black is a very capable platform, (that's why I bought it) but the Raptor is supposed to be super-awesome-o 9000 so yeah.

Thank you in advance for any and all advice and feedback anyone may provide in this matter.

Rig, for what it's worth:
Phenom II X2 555 unlocked to X3 OC 3.6
CoolerMaster GeminII S
ASRock M3A770DE
XFX Radeon HD 5830 OC'd to somewhere I can't remember at the moment (Soon to be a 7850 or NVidia's answer to that price range, whichever performs better.)
SeaSonic X750 Gold
CoolerMaster Elite 430