Incremental backups = full hard disk drive (sooner or later)

It seems to me that Vista's built-in backup supports only 1 model: a full
backup the 1st time, and incremental backups forever thereafter. Since I back
up to an external hard drive, this is eventually going to leave me no option
but to delete all my backups and start over from scratch.

1. Am I missing something in Vista's built-in backup?

2. Acronis True Image Home seems to be the most recommended 3rd-party
option. Any objections? Their Web site implies support only for 32-bit Vista
(by mentioning 64-bit XP explicitly, but NOT 64-bit Vista). Does it support
64-bit?

Thanks for your input! -Doug