Windows 7 - win7 setup from diff. partition/hd

i have 4 hard disks and LOTS of partitions
80gb , 160gb , 320gb , 1000gb
windows 7 = in a partition in 1000gb
all other partitions are normal partitions with data.
my current Windows 7 is upgraded from vista thru a dvd. now after lots of months. im having probs and want to format and reinstall windows.
BUT i dont have a disc drive anymore.
now i have made a small partition in 160gb . made it FAT32 . set it ACTIVE. and put win 7 iso files there. when i boot 160gb HDD . it boots up fine . win 7 setup comes. helped me repair probs a lot.
when i boot 1000gb . my current windows loads.

so i wanted to format 1000gb and install windows there agian now. but i thot i will just confirm that Windows 7 setup COMPLETES smoothly from that 160gb hard disk.

so i booted 160gb HD . started setup and installed a trial windows in 80gb hard disk.
setup completed successfully.
BUT sadly i notice. that if i BOOT 80gb hard disk . nothing happens . if I boot 160 gb hard disk . then the new trial windows @ 80gb comes. booting 1000gb brings my current windows as normal

so WOW . im having this problem. if someone helps me with this ill be GREATFUL!
i want to install windows from 160gb partition on 80gb or any where such that I boot that hard disk and windows comes instead of booting my 160gb hard disk.

plz help

Hi

Have look at these tutorials:

Clean Install Windows 7

USB Windows 7 Installation Key Drive - Create

Also look at the tutorials inside the links.