I've been workin' with a 450D and two kit lenses for the past 4 months. I am now looking to purchase a single Alienbee strobe to sorta complete a very basic setup..

Note: I have used the built-in XSi flash.... it's not great, but it is definitely cheaper than the 430EX II, which BTW, I /do not/ own.

Q: Would it be absolutely necessary to also have a kickass Speedlite? In other words, is it possible to really, truly, pull off professional shots with one strobe light? I'm confident that one light is better than no light, as long as that light is not the flash I'm working with built on to the XSi.

Okay, I'm leaning big-time towards strobes. I've done a lot of research within the past 4 months regarding lights, but you know with knowledge comes many questions! =]

Obviously, I am fresh meat in the dSLR world, too. So lemme get this straight: External flash (that is not EX-series) will /need/ a _PC adapter to sync up with the XSi_... do I understand correctly that I will need to purchase a PC Sync Hot Shoe for 10 bucks on Ebay?

Also, I'm not even rich to most poor people. Thus, I can only currently afford a AB800 strobe, or the 430EX II, but certainly not both!

Fact: I really want a strobe, is there anything I should be made aware of? That is my concern.

I could really use some friendly advice! Thanks!