I agree with Johnnick on everything he said, (and I have both the PS2 and DC versions) just wanted to add that I've also heard from members on Shoryuken.com and SNKCAPCOM.com (scene people) that the Xbox version, as it came out after the PS2 version is the most arcade perfect insofar as its identical to the PS2 version gameplay wise (already a great thing) but also has arcade perfect resolution which allegedly the PS2 version was either slightly off, or had the right ratio at a different resolution so the sprites were not as crisp onscreen as the arcade version. I can tell you that the DC version was completely off resolution wise (plugged in both systems side by side to do comparisons) PS2 version looks just like the arcade res, but again the sprites are a bit fuzzy (allegedly the Xbox version's is not -- though i've not played the xbox port).
Long story short, get either the PS2 or Xbox versions, both are identical, but get the Xbox version if you want sprites as clear as possible (fuzzyness on PS2 is not noticable really, just saying from the arcade perfection standpoint).
If you got a 'box, get it for that, end of story :D
P.S. After you get that game, be sure and get a good adapter for your sticks ;) Go to http://www.liksang.com">http://www.play-asia.com">http://www.liksang.com or [url]www.play-asia.com if you don't already have a place to get em.
If you live in the US, the Xbox version is 20 bucks, and the adapters are like 15-20 bucks each, still all told, alot cheaper than your original options 1 or 2 heh.