My 2c: If we'd had this conversation 6months to a year ago (or we were talking PSOne to two) I would have said maybe a ps2, but it just doesn't make sense anymore. The list of good games still to be released on the PS2 is about, well, 1. The list of AAA titles for the 360 for this year alone is enough for me to look at remortgaging my house!
In the old days you may have needed to sweat the Psone for a while while the PS2 driopped in price, I did. But the 360 is available now, and it's not "just a stop gap to the PS3", comparing it to a PS2 is an insult, frankly it outclasses the PS3 in almost every respect. (having to pay for Wifi is the only sore point in my book)
On the SDTV issue, it's bollocks, straight up. Yes 480p is "fuzzier" than 720p, no duh! But the texture quality, lighting, physics, AI are a lot more than "pixel count".