Everybody has the size issue nailed, I think; to add my bit, I'm a proportionately built 6'4", and 62-63 cm is usually about right. I can go down as far as 60cm by raising the bars and seat a bit. Keep in mind that this varies, though, in that the seat tube measurement isn't the only thing that governs fit, and the geometry of the bike has a huge impact.

At your height, I'd pass on a 65cm (and from the looks of the pictures, that's a legitimate measurement) unless you had a chance to ride it first. I cruise eBay looking for great deals in my size pretty regularly, and can tell you that for $75-$175 plus shipping (note: eBay is more expensive, by and large, than Craigslist, garage sales, or thrift stores ...) you can pick up a nice bike of a brand equivalent to Univega, like Nishiki, Centurion, Shogun, Fuji, a little more for Miyata, etc.

Good luck.