OnLive for me is huge. I still haven't got in, but I am really excited too. The reason I never got into PC gaming was the money. I never wanted to invest in something that much when I could play on a console. But now, I don't need an amazing computer. So, am I I the audience they are aiming for? And if so, is it really a big one?

well do u have good internet? 
one important thing however is that they dont have this game... yet 

Onlive's target demographic are stupid people so no I would not say you are their core demographic.
 
Now there is always a chance it could get better but right now its $192.00 for the service with full retail game prices. Zero compatibility with Xbox Live or PSN. No guarantee of higher resolutions than what they use (480p?). No guarantee or it even existing past this year. So the best advice is just to take it with a grain of salt.

" Onlive's target demographic are stupid people so no I would not say you are their core demographic. 

Its 720 and it is in theory a great idea being able to play on a cruddy computer high-end games and then be able to take those across platforms(With the soon to be released Ipad app)    

PC gaming is already cheaper than console gaming..  I don't see the appeal of this service at all.

I do love the idea of strapping $300 dollars worth of peripherals to an iPad to play Starcraft 2. It's times like this where I hate myself for not knowing Photoshop.

If you've got fast internet and no internet caps, then that's a goodstart. However, keep in mind that even if you supposedly buy an OnLive game that at a certain date (I think most games are around 2013), they have the right to stop providing service to you for those games. While Xbox Live also has this clause, they only really shut down the original Xbox game support this year. Whether OnLive have included that as a legal clause or something they are actually going to do is yet to be seen.
 
Add on top that you need a consistent 3MB to 5MB connection to maintain a standard def experience (I know they've claimed the lower end of the spectrum, but in the real world that's what I hear people are saying) and the subtle lag in the experience, and I think that OnLive is not a good alternative to actually having the game. Oh yeah, and you need to a subsciption just to access the service! At the moment its free, but in a year's time that's going to chance. If you really want to play a PC game without a good PC, then the only suggestion I would back is getting the console equivalent.
 
In a similar way to how Microsoft were pioneering tablets for years but it took Apple only one attempt to make their tablet (the iPad) a success, I have a feeling that OnLive will be looked back on in a similar manner - as an interesting technology that is sadly ahead of its time. 

If it's a multiplatform game then the console version will always be superior to the OnLive version in many ways (graphics, control, not using excessive bandwidth, not having the game revoked, not paying yearly subscriptions).
 
If it's a PC-only title that actually appears on OnLive (a few will), it may be worth it.  You don't need to spend much to have a better PC than what OnLive will stream.

I like to physically own my games for the most part, so I would never get OnLive. It feels wierd getting downloadable games, let alone paying for that service.