Hello, and welcome to the forum !
As you of course know (having read the FAQs) CHDK is not a firmware update but a transient program.
So, it is logical that it will be gone on cam shutdown ! If you want it to to autoboot (using DISKBOOT.BIN)
2 things are vital:
1) the file system should be FAT16 and 2) the card should be write protected
These are restrictions imposed by the Canon firmware (CHDK later tricks the cam into ignoring the write protection)
The FAT16-only restriction is especially painfull, since it is impossible to format cards > 4 Gb with it ...
re-read this FAQ:
http://chdk.wikia.com/wiki/FAQ#Q._How_do_I_get_CHDK_onto_my_camera.27s_SD_memory_card.3F (especially "Notes" at the end)
Sorry to hear that CardTricks doesn't work on Win 7, but hey, it
is a beta OS - if the trend set in with Vista continues,
i sincerely doubt that you're gonna be able to do any low level stuff on your SD card with it ...
The guys from Stereo Data Maker
http://stereo.jpn.org/eng/sdm/index.htm have come up with a utility to partition SD cards,
but i have no idea if it works on Win 7 (attached)
More info on making your card bootable is in the Wiki here:
http://chdk.wikia.com/wiki/Bootable_SD_cardhth,
wim
edit: oops, missed that you mentioned a 2 Gb card. Then it's just the OS, prepare your card on XP or (shudder!) Vista ...