This deal has ended.
Dell Small Business now has this Optiplex 750c Minitower on sale for only $449. This is definitely a business-class PC: it comes with an impressive three-year on-site warranty, which normally costs $250 or more. It also comes with a 17" LCD monitor, 1.86 GHz Intel Core 2 Duo processor, 512MB memory (this I would upgrade: either 1GB for $15 or 2GB for $65), 80GB hard drive (upgrade to 160GB for only $10), 16x DVD-ROM drive (upgrade to a burner for $13), and Windows XP Home Edition. Shipping is free and sales tax is charged in most states.