Is it possible to mirror from a G5 to a Cinema display?

Question

There was a recent post here that addresses this, but my (likely very stupid) question is--isn't it possible to use a mini vga to vga and a dvi to vga adapter to connect your iMac to a Cinema display? Or does the dvi to vga adapter only go one way?
I'm assuming from the thread mentioned above that this is essentially impossible without a lot of finagling. The website for converters linked shows a VGA to DVI-A converter, but I'm assuming DVI-A is different from DVI?
I was originally told by an Apple store salesperson--who, in retrospect, clearly had no clue what he was talking about--that the Cinema display would work with my iMac, no problem.
Unfortunately... I bought a second-hand one off ebay, so now I'm stuck with a monitor that I can't even check the display on (which will probably make reselling it on ebay difficult.) So I'm trying to figure out once and for all if this is impossible and I should just give up, cut my losses, and get a VGA display instead.
I went into the Apple store today and the ditzy girl I spoke with informed me that "the people in the back" said that it wasn't at all possible to mirror my G5 onto a Cinema display. She clearly didn't know anything beyond what size ipods they carry (if even that), so I'm hoping someone a little more knowledgeable (or maybe even someone who's tried it?) can clarify for me, because the extent of my hardware-related expertise is 'how to install RAM.'
Thanks in advance for any help!
(And lesson learned: never count on Apple store salespeople for any information--ever.)

Answer 1

Thanks for your response Donna! Further research has found me some more clear-cut answers.
I've read a few success stories of people using the VGAtor to convert their iMac's output from VGA to DVI but I'm apprehensive since it costs $300, and there's no mention of a return policy on their website that I can find. I tried emailing them about compatibility/return policy so I guess we'll see. (The success stories I speak of are in the forum for Screen Spanning Doctor, but the forum's been dead for almost a year now.)
Gefen's VGA to DVI Scaler seems to be better supported, but that's up to $330.
I don't want to use a TV, because I'm a graphic designer so I need higher resolution than any TV in my price range can offer.
But I think I will probably be going with a VGA display though just to save myself the headache. Even if I ended up losing $300 in reselling this display to get one, it would be no different than spending $300 just for a converter--I'm not convinced that the Cinema displays are worth it, when I could get something similar for under $400. If I had wanted to spend $1000 on this upgrade I would've just sold my G5 for a new 24" one.
I agree it would've been much smarter if they had just made their own DVI adapter, since they DO exist (and enabled screen spanning in the G5, at that.) Or, even more radical... just added a VGA input to their displays--there are plenty of monitors out there with both, so obviously it's possible. If they had actually made the displays compatible with like 90% of their pre-existing systems they could have sold exponentially more. It would have been far more profitable--I love Apple computers, but I'm sure I'm not the only one choosing to buy another brand of monitor rather than fork out thousands to upgrade the display of a perfectly good computer.
Well, forgive my rambling. In case someone else is curious, I'll wait to see if I get a response to my email, then update and close this.
Unfortunately now I've gotta lug it on the metro to get it tested, since taking it to the Apple store seems to be my only option right now.