Second on the desktop. Do what I did when I bought my laptop (a Toshiba Satellite Series L305-S5933). Scour Newegg.com for the best deals. Don't focus on the price so much - look for the features. I needed a "desktop replacement" notebook, so I went with power and size. 250 GB hard drive, 3GB DDR-2 RAM, Intel Pentium Processor T3400, DVD SuperMulti, 802.11b/g wireless, built in camera and microphone... granted the battery only lasts for two hours, but that's expected of a desktop replacement. It's meant to be plugged in, with the battery being a backup power source.
The cost? $499. No taxes, no shipping charges. Just $499 straight to my door from Newegg - I could have gone for the credit option, but I wanted to ensure it was paid for OOB (out of the box).
Now, back to NewEgg. Once you've figured out what you want feature-wise, then start looking at the price. With a few exceptions (HP, Compaq, anything containing an ATI card or AMD processor these days since AMD's quality has IMHO gone down the toilet the past few years), don't worry about the brand. Just find the best computer that matches your "wish list" at the lowest price and go from there.
One note about Toshiba laptops - the hinges are flimsy, and will break after about a year of use if you constantly open and close the notebook - you know, treat it like a laptop. So do keep that in mind.