Computer Bag Recommendations

I'm in the market for a new computer bag. Probably a backpack, but I'm open to suggestion that might sway my decision.

I'm still using a black leather clamshell bag that came with my Gateway laptop 7 years ago. It works, but only because it's on-hand. I'd really like something new (read: without ripped out zippers from stuffing too much crap into the pockets).

On a different note (but strangely related), I was surprised by something recently:

I haven't flown in probably two years (possibly three). And, at that time, I was staying at the destination for a week, so I had luggage to check.

In a couple weeks, I'm going to be flying out to San Francisco for a few days, and then flying back. Now, in the past (pre-September 11), I would have just carried everything (2 pieces) onto the plane and not worry about checking a bag. But, I read on DTW's web site that they only allow one carry-on. WTF??!

So, since I can't stuff 2-3 days worth of clothes into my laptop bag, it looks like I'm forced to carry-on my laptop, and check a duffel bag. What are the chances that I'll be buying clothes in SFO due to luggage lost by the ground crew of a bankrupt airline (NWA)? Luckily, it's a direct flight, so they won't have to transfer my bag from one plane to another.

In conclusion, I think I'd also be interested in any computer bags that could accommodate overnight clothes and toiletries as well (serving as my only piece of carry-on luggage).

UPDATE (10/24/2005): Thank you to Aaron for pointing this out: A laptop qualifies in the same category as a purse (albeit, a MANLY purse). The 1-piece of carry-on luggage is in addition to your purse (it's EUROPEAN!).

From the DTW FAQ:

How many carry-on items are passengers permitted to take through the passenger-screening checkpoint?

Passengers are limited to one carry-on item along with one personal item, such as a purse, briefcase or laptop. Check with your airline for specific security and baggage requirements.