General Purpose User
These days, $500 to $1,500 will get you a desktop with enough power to run productivity apps, view and edit vacation photos, manage MP3s and videos, and even play many of today's games--the core activities most common to families, students, and the general purpose PC user.
Spend around $500, and in most cases you'll still be able to view and edit vacation photos, manage MP3s and videos, and even play many of today's games. In most cases you'll still be able to run common tasks without delay, although extreme gaming becomes a stretch.
Dell, HP and Acer are good budget, general purpose choices. No Frills, just basics.
Power User
It's easy for the price to get out of hand with a power PC. If you shop around, you should be able to find a more than adequate gaming or digital design box for between $2,500 and $3,500. You'll need a large, fast hard drive--perhaps two or more if you plan to transfer and edit movie files--and of course, a DVD burner or, if you have an HD display, a Blu-ray or HD DVD drive.
Dell, Sony and Gateway make decent entry level gaming PC's. For Digital Design Apple/Mac cant be beat.
Media Center functionality is built into Windows Ultimate and Home Premium, so you could make the argument that a home-theater PC doesn't need its own category anymore. You don't need all the power of a traditional desktop to simply watch downloaded movies and listen to music. If you demand high video quality, you might sacrifice some of that capability if you opt for a lower-end system.
Dell, HP and Apple make great media center computers.
Design is definite Apple/Mac, but for the most part a budget low end PC will do any home office just fine.
