I've personally never owned nor operated Windows 7 on any of my systems. But once upon a time I did run Windows XP and even running that I always tried to get my hands on service packs when they became available. (SP1) to (SP2) and finally (SP3) when it came out, I was there "ready and willing"!
Please do yourself a favor, just download the service package and install it, it was created and released for your Operating Systems greater good. Plus some programs out there are (service pack) dependent, don't have the pack, you don't get to use the program! Also if you don't have the pack, you don't get the enhanced stability. And last, you don't get the pack, you don't get the additional fixes and security!
It's up to you, I'd get it, but that's just me!