That shouldn't be necessary if the two are compatible. The BIOS should show 4 gigs regardless, remapping is for shifting RAM addresses above the PCI Bus boundary.
http://support.microsoft.com/kb/929605
The memory doesn't have to be remapped in my current two systems that have four sticks, the memory is NOT rempped yet shows 4 gigs in Bios and in Vista 64. The other system runs XP and shows about 3.38 gigs. Indeed remapping can cause application and driver incompatibilites with older software. And it's NOT good for XP! Memory remapping versus full compatibility with four sticks seems to be a topic that hasn't been examined.
Oops, an addendum. I checked the XP system and only 3214 megs are showing in BIOS, with remapping it now shows 4096 (3250 in XP) However that unremapped value is different from the OP's 3007 Megs, which is what I had on the other memory, so it goes....