Sorry I've got so many questions here, but I was wondering how I can get the best performance out of Windows XP on a Dual 1.8 G5. I've tried Virtual PC 2007 but it only allows 16MB VRAM and emulates a very slow CPU that doesn't allow pretty much any programs to run on it. I've heard of emulators like Q but I can't find a working download link for it anywhere.
For emulating XP on the G5, VPC 7 is as good as it gets.
You're better off lowering the VRAM enough to match your display output and don't use all of the 512MB RAM - it actually decreases performance.
Turn off all options you won't be using (networking/USB etc) and slim down XP to the bare bones - this will give you a fractional performance gain but not much.
If you can go to an earlier Windows version you will see an increase in UI response - Windows 2000 offers good compatibility with XP but 98 and 95 are much faster.
My personal experience is that VPC can sometimes run software designed for faster machines - painfully slow to the point of being useless - but is generally comfortable emulating a PC around the 200Mhz mark - it all depends on the type of software you're trying to run too.
There's a thread about it here:
https://forums.macrumors.com/threads/has-anyone-played-with-virtual-pc-2007-lately.1898836/