So you've already decided: Your new PC must have the fastest processor available. And if you're going to be running Windows 98 in a home or small-office environment right now that processor will be either an AMD Athlon or an Intel Pentium III. Both CPUs are available at speeds up to 600 MHz and in the case of the Athlon up to 650 MHz. That should be enough to keep any budding Web surfer, financier, or even low-end Web content creator happy. Add a high-speed cable or DSL modem and you're off to the races. Going strictly by the numbers, the edge in speed goes to the Athlon. As we found in testing for this story, the Athlon just squeaked past the PIII on business applications, as shown by our ZD Winstone 99 benchmark tests, as well as on some 3-D apps as shown by our ZD 3D WinMark 99 benchmark tests (see ZD Benchmarks tests results table). The Athlon's prowess on integer-based code was readily demonstrated on our ZD CPU mark 99 tests. Clock for clock (in this case, at 600 MHz: there's currently no PIII/650), the Athlon outperformed the PIII by 27 percent. Part of the reason for this performance difference is design -- the Athlon has microarchitectural advantages over the PIII that translate into higher performance on both integer and floating-point code. On the other hand, the results from our 3D GameGauge tests were just too close to pick a definitive winner. Since GameGauge includes games that are coded to take advantage of both AMD's and Intel's specific multimedia instruction sets (3DNow! and SSE, respectively), neither processor enjoyed any competitive edge during testing(see Gameguage 2.0 results table). For many consumers in the market for a fast PC, there's more to the equation than benchmark test numbers. But if speed is all you care about -- and you must have every last ounce that you can get -- the decision is easy: Buy an Athlon machine. But the rest of us (the vast majority, we'd argue) consider many other factors that go beyond the hardware specs -- including service and support, ease of use and setup, quality of the software bundle, and warranty -- just to name a few. In a new roundup from PC Magazine, you'll find four very fast PCs, but you'll also find that each has a story. The Athlon-based Compaq Presario 5861 is a great family entertainment machine, with perks such as a THX-certified speaker system, hooked to a four-channel positional 3-D audio card. The Dell Dimension PIII machine offers offers great hardware, a generous software bundle, exceptional online support, and a year of Internet access from Dellnet.com included. The IBM Aptiva S Series 860 Athlon machine is definitely the best looking -- the unit is also the fastest system here, and it comes ready to be networked in your home.