I'm in the pro-filter club myself. I'd rather replace the filter than the lens.

As to which one to buy, buy the best you can afford. I will eventually have Hoya Pro1D filters on all my zooms and Hoya HMC filters on my primes, which are all 49mm (would've gone with Pro1Ds, but they don't make them that small). If you want to get your UV filters cheaper than the traditional camera stores, check out
Camera Filters The Filter Connection 2filter.com for Hoya HD filters, Hoya Pro 1, Tiffen HT, Tiffen 4x4 Camera Filters, B+W filters and Canon Inks.
HTH,
Heather
