I think I may have found a solution (other than VirtualBox) to the >2GB RAM problem with Armada I on Vista/Windows 7. I'm posting it, because it seems like no forum that turns up on Google searches of the Armada RAM issue have this.
While on XP one could use /MAXMEM in boot.ini to set the detected RAM to 2GB, this wasn't there in Vista and 7.
I decided to see if there was an equivalent; Google-fu turned up this page:
So, doing this:
bcdedit /set TRUNCATEMEMORY 2139095040
In an (administrative) command prompt, should do the same thing as setting /MAXMEM in XP's boot.ini.
When you're done playing, using this in a command prompt:
bcdedit /deletevalue TRUNCATEMEMORY
To restore your full RAM amount.