If the $1700 includes a monitor, you should be able to include a cool 17" (maybe more) flat panel.
If you must go brand name, Dell is probably the best choice. Building one is not hard, it's fun, (and educational!) You won't save a ton of money but you'll get much better components and a lot of expandability. Dell, Gateway, etc. are often hard to upgrade or expand because many of their components are proprietary, i.e., limited to that machine or manufacturer. If you go brand name, get a machine configuration that will last you 3 0r 4 years. Go for at least 512 ram; Windows XP pro instead of XP home.
A middle ground between brand name and build-you-own would be a "white box" PC from a local computer dealer. They can build them to your specification with quality components and give a warranty just like the big guys.