Buying New Low-cost, high-power components make a compelling case for upgrading your existing PC. Still, many users might be better off purchasing a new system if performance is what they are after. Over the past year, a number of crucial new technologies have landed on the system motherboard, delivering improved performance. Among them: PCI Express: The successor to the long-standing AGP graphics bus, PCI Express pushes more bits to deliver higher performance for top-end graphics cards. Some graphics cards, like those based on the ATI X700 GPU, are showing up first for PCI Express and later for the older AGP standard. Purchase a new PC with PCI Express capability, and you'll be able to run the best graphics software for years to come. Serial ATA: The ATA connector found inside almost every PC produced through 2003 is now as old as dirt. Last year, PC makers began shipping systems with Serial ATA. While the first SATA drives weren't appreciably faster than those using the last ATA standard, called ATA-133, the updated version of SATA changes that. Called SATA II, this connection runs at a speedy 3 gigabits per second (double the 1.5 gbps of the original SATA). The first SATA II drives are appearing on the market, including the massive Hitachi Deskstar 7K500. Both types of SATA connections pay dividends by reducing cable clutter and helping keep the inside of your PC cool. USB 2.0: If you bought a desktop two years ago, you probably missed out on this major update to the popular USB connection. USB 2.0 can push data at up to 400 mbps, fast enough to support external hard drives, DVD-writing drives, and even TV tuners and video-capture modules, among other neat devices. You can add USB 2.0 to older PCs by installing a PCI add-in card (expect to pay $80 or more for something like the Adaptec USB 2.0 Upgrade Kit), but newer PCs provide these connections out of the box.