@FallenOneX: I've been using Windows 7 x64 and Debian AMD64/EM64T (which is the Intel x64 version) for a while now, double booting with GRUB 1.5. Ubuntu is a Debian derivate, so it should be the same. The easiest way to do that, if you have more than one hard disk, is to unplug the one you want to put Ubuntu in and install Windows 7 on the still plugged in one. Now go to Control Panel>System and Security>Administrative Tools>Computer Management>Storage>Disk Management. There should be an unmounted partition (with no drive letter) called System Reserved. Assign it a letter and remember not to touch it. After that, plug back in the linux hard disk, and install Ubuntu on it, choosing GRUB 1.5 as your boot loader. Windows 7 is usually not recognized, so go edit your /boot/grub/menu.lst (sudo gedit /boot/grub/menu.lst or just login as root) and add these lines title Windows 7 root (hdx,y) savedefault makeactive chainloader +1 the options x and y under the root argument are to be replaced respectively by the number of the Windows hard disk (starting from 0) and the number of the System Reserved partition (starting from 0). In this case, it should be "root (hd1,1)". Try different combinations, it'll work!