advice for purchasing a fixed gear
 

A fixed gear is not a toy! :p :D

kilo tt or windsor hour

Lots of good bikes out there. I got a Cayne Uno and I really like it. If I'd been willing to spend more money, it would have been a Surley Steamroller, or a Masi Speciale, or a Bianchi San Jose. Probably the Steamroller.

id say be confident that you want a fixed before you actually commit to buy one. make sure youre confident riding one in traffic and also your girl is too if you want her riding it. a front brake perhaps till youre good. A rear hub threaded for a flip flop in case you ever want to run single speed. If you said you dont want to worry about it being locked up or stolen, I wouldnt invest a few hundred in a brand new one either. Convert an old frame

+1

Front brake until you're good? Front brake AFTER you're good, too. There's nothing cool about getting killed, and that front brake may mean the difference between a wrecked bike and a not-wrecked one even if you ARE good. And if you use a flip-flop hub, get a back break too.

run brakes always on the street for serious riding. i put my brake on if i'm biking in traffic, if not both of them.

...seemed more to me like "he" was the girl that "he" was talking about.

but yeah, on the not too expensive but good quality front.

kilo tt from bikesdirect.com is the cheapest quality option.

IRO irocycle.com is probably 2nd on the list with a slightly higher pricetag and a higher quality option.

otherwise any major manufacturer has a complete entry level bike somewhere in the +/- $600 range

conversion

I've found that it is now fashionable for most major bike companies to have at least one fixed/ss bike in their 2008 lineup. Most have a flip-flop hub so you can decide whether you want run it fixed or ss depending on your mood/confidence/ability. I have seen a Schwinn Madison, Bianchi Pista, Kona Paddy Wagon, and I know there are heaps more by Cannondale, Masi, Trek, Fuji, KHS, Salsa etc.

I toyed with the idea of building from scratch but unless you already have a good frame with horiz. dropouts or lots of spare parts it would be much easier to order a complete bike.