See if you can access the one-time BIOS Boot menu to boot into XP HD now. Look for the key on BIOS Boot Screen to tap repeatedly at bootup or use one of these:
Asus - F8
HP/Compaq - Esc
Sony - F2
Acer - F12
Gateway - F10
eMachnes - F10
Toshiba - F12
Dell - F12
IBM/Lenovo - the blue Thinkvantage button
Next see if you can open your User folders on G from C. If so, we can help you link and move your C User folders to G which can then act as a data drive for C and even for XP if you want. This is the best arrangement for a smaller SSD - to move the User folders to a larger HD.
User Folders - Change Default Location.
If not, do you have a place to back up the files you want from G long enough to format it?