Dell Deal
Through May 2, Dell Dimension E520 desktops are $280 off (use this e-value code: DDDWAR4—that info's also on the website). This specific model (which uses Intel® CoreTM 2 Duo processor) is rated as a "best buy" by Consumer Reports for features, performance and price point.
The deal also includes a 20-inch widescreen digital flat panel monitor, which is a nice upgrade. Again, their offer expires 5/2/2007.