Like Seeker, I've had good success with Acer laptops in the last few years. I've also seen many other brands do just as well.
I've bought three Acers in the last five years or so and they are all still going strong.
The oldest one still runs BiaB/RB just fine and all of them were about $459.
It's a dual core AMD (2.3 gHz) with 4 Gig RAM and 350 gig HD.

If it was me at this budget I'd look for an AMD processor dual core above 2 GHz speed (minimum), 4 Gig RAM (minimum), Win7, decent HD size, and then after purchase I'd clean it up.

To clean it up - take it home and spend an hour removing all the stuff you don't need that comes pre-installed.
Ditch the antivirus free 6 month trial (it ends up needing replacing anyway).
Ditch the 'toolbars' that waste resources
Ditch the Free Anything that you truly do not need.

Set it up/clean it up right after purchase and most current machines will work fine.
That's my experience anyway.

Make your sound your own!
.. I do not work here, but the benefits are still awesome