Environment: Mac OS 10.5, VMWare Fusion 1.1.3, Windows XP Home SP3, MS Office 2007 SP1.
How to get the Apple Remote working in the Windows guest OS (found the solution in the VMWare community pages):
1 - Enable IR Receive in Fusion
2 - WXP installs a driver
3 - Get Bootcamp 2.0 Windows drivers for 10.5 (found them through Google...)
4 - Install IR driver
5 - Get ARW from http://sourceforge.net/projects/arw and install
This works for me and I can fwd/rwd slides inside the virtual machine.