To the OP...
By the sounds of it, you intend on switching to Windows 7 as your main OS once it's in final form? I say this because you said "Vista is my main OS for now..." Ok, so going by that then why not just mess around with Windows 7 the way it is for now (so you can see what it can and can't do) (as Kyle said, there's no way to make a Lite Win 7 installation as of yet) then once it's released in final form make the switch to it as your main OS..

I also am still using Windows Vista (and will continue to do so after Win 7 is done and in stores, triple boot configuration) but in the meantime I'm using 7 just as much..

It's that good and that rock solid...
Also, I'm not sure what else you want to remove from Windows 7.. as it's already very streamlined compared to Vista.. with things like Messenger, Mail, etc all being removed from the installation there's not really a large number of things left to take out... a few but certainly not as many as Vista for example...
I'd also suggest allocating more than 10GB's of space if you can spare it.. for Windows 7 to run as intended it's recommended that you use at least 20GB's of HDD space.. That's not to say 10GB won't work, because 10GB WILL work, obviously. it's just for 7 to run the best it can 20GB would be a better amount..