Btw, my system is infact using 4088MB of the total 4096MB and I'm using XP 32bit
OS sees 3327MB and the unmanaged 766MB is allocated as a RAM disk so only 8MB of the total 4096MB is wasted.
And the funny thing is; I have a HD4890 with 1024MB of GDDR5 and OS has >3GB usable, so the quote from OP is not correct.
4GB system ram
1GB video card
3GB system ram usable, 2GB left in games once video card ram is duplicated.