Hi,
The very first thing i would like to share with u is the entire registry cant accomadate on ERD. It stores only the partial part of registry. Mainly it stores uesrs name with their current passwords, copy of ntldr,Boot.ini, ntdetect.com, ntoskernal.exe, your harddisk's information (Volumes, stripe sets, mirrors) and i mentioned earlier it stors some strings and keys of registry.
To use the ERD you have to have three NT setup disks or Windows NT's CD. To use ERD boot your NT machine with three setup boot foppies or CD
if you are booting through floppy than after inserting 3 rd disk it will ask for repair or new installation. Press R to repair than insert the ERD restore the files which is required.
If you are booting with CD than keep your eyes on repair or new installtion screen than follow the same which i mentioned earlier.
Thanx & Regards
Abhinav