Stardock's Multiplicity allows Windows users to operate more than one PC at a time. This $30, Vista-compatible software, which works over your home network, enables you to control two PCs with one keyboard and mouse.

During setup, you designate one PC as the primary machine on your network, and it controls a second system (the $50 Pro version lets you control up to six other systems). A 15-day trial is available.

Mouse movement works the same as in a dual-monitor setup, with the cursor traveling between two displays as if they were one. But with Multiplicity, you have full mouse and keyboard control over two PCs. This machine-switching mode worked well, though the mouse sometimes lagged between the two screens for a few seconds.

The two PCs share a clipboard--a handy tool for copying and pasting images or text between machines. Only the Pro version lets you copy files and folders back and forth between computers, which is one of the program's best features.

Don Reisinger