Gilbert,
From Mactopia (bottom of page)
http://www.microsoft.com/mac/downloads.mspx?pid=Mactopia_VPC&fid=BB545A70-CC7F-4 902-B7B1-8E9D4ED665D2#viewer
_System Requirements (for Virtual PC 6.1.2)_:
+Before you can install this update, the Virtual PC for Mac 6.1.1 Update must be installed on your computer.+
+In addition, your computer must meet the following minimum requirements:+
+Processor: Macintosh PowerPC, native G3 or G4 machines (Intel processors are not supported)+
+Operating system: Mac OS 9.2.2 (Classic) or a later version of Mac OS+
+Memory: 192 MB of RAM+
+Hard disk: 60 MB of available hard disk space is temporarily required to complete installation; after installation, the program requires 30 MB of hard disk space.+
+Programs: Virtual PC for Mac 6.1.1 must be installed before you download this update.+
+Internet access: Internet connection through either an Internet service provider (ISP) or a network. Internet access might require a fee to an ISP; local or long-distance telephone charges might also apply.+
+Tip If you're not sure whether your computer meets these requirements, see the Apple System Profiler program included with the Mac OS. If you are using Mac OS 9.x, you can start Apple System Profiler by clicking Apple System Profiler on the Apple menu. If you are using Mac OS X, you can start Apple System Profiler by double-clicking its program file in the Applications/Utilities folder on your hard disk.+
_For Virtual PC 7.0.3 (the last version)_:
+System Requirements+
+Before you can install this update, one or more of the following programs must be installed on your computer: Virtual PC for Mac 7.0 through 7.0.2.+
+In addition, your computer must meet the following minimum requirements:+
+Processor: 700 MHz native PowerPC G3, G4, or G5 processor (Intel processors are not supported)+
+Operating system: Mac OS X 10.2.8 (Jaguar) or a later version of Mac OS. G5 processor requires Mac OS X 10.3 or 10.4.1 to run Virtual PC for Mac.+
+Memory: 512 MB of RAM+
+Hard disk: 70 MB of available hard disk space is temporarily required to complete installation; after installation, the program requires 50 MB of hard disk space+
+Internet access: Internet connection through either an Internet service provider (ISP) or a network. Internet access might require a fee to an ISP; local or long-distance telephone charges might also apply.+
+Tip If you're not sure whether your computer meets these requirements, see the System Profiler program included with the Mac OS. You can start System Profiler by double-clicking its program file in the Applications/Utilities folder on your hard disk.+
Bob