I know it's now 2017 and it's unlikely a lot of people do this, but I have a client who asked me to do a dual-boot computer with XP and Win 7. A VM was considered, but he preferred a dual-boot system. The computer has an SSD and for performance and TRIM reasons, we wanted it in AHCI mode.
Since the computer doesn't have a floppy drive, I had to go through the process of using nLite to add text-mode drivers for the SATA/AHCI mode. That's a lot faster than I remember it from 13 years ago. :)
Now I had to do the dual-boot. There were a plethora of articles about how to do the dual-boot and they all work well.
I had a Clonezilla image of a 32GB SSD into which I installed Win 7. I booted to the Clonezilla thumbdrive, restored the drive image, booted to Win 7, went to Disk Management and expanded the C:\ partition out to all but the last 80GB of the SSD. So far, so good.
I then installed Win XP and that is when the challenges started. The XP setup saw the little 100MB partition and larger partition for the Win 7 install and assigned them C:\ and D:\ respectively. Once XP was installed, it installed to a different drive letter. It wasn't a huge deal to me, personally, but my client is likely not savvy enough to change the installation path of every program he's going to install once I give this to him. I really wanted a solution where each OS saw it's own C:\, and not the other OS's.
The search for that solution brought me here, and Velcro turned me onto GAG Bootloader. That completely solved my problem.
I had to go into Win 7, delete the partition with the XP install on it, then create a new primary partition.
I then booted the computer to the GAG CD that I burned from the provided ISO. I could then add a new entry. I saw three partitions and selected the first one in the list, labeled it "Win 7", then added another entry, selected the last partition, labeled it "Win XP". I then went back to the main menu and selected the option to hide primary partitions, then saved it to the drive.
I now can turn on the computer, get to GAG's menu, select either OS option and it boots, the computer only sees a C:\ drive and not the other OS's partitions.
Thank you for your help and I hope this helps someone else avoid a few hours of challenge.