He has the situation where the boot files are in the System Reserved Partition.
Can you reinstall Win 7? If you do, pre-partition the drive and format that partition so you do not get the Reserved partition.
The most important thing about installing in a dual boot situation is to determine which drive is primary. If you look in the bios, there is a drive order, not boot order, listing. The first one listed is the primary drive. The SATA connectors determine which drive is drive 0.
In your case, you installed Win 7 with the new drive listed as primary, so Win 7 made it own special partition, but it did not see the XP drive because it did not need to. setting up a dual boot with independent OSes is not a problem, but doing it with the system reserved partition adds new challenges.
NOTE: I have heard the reserved partition may be used for bitlocker. If you are using that, you may not want remove the partition.
Don't worry about the chipset
drivers for now.