I am in the process of Tagged about 30,000 photos using LR3. All of the photos were saved in separate folders under "My Photos" in Windows 7. Now, since my C drive is nearly full, I am installing a new drive in my PC. I plan to copy all the photos from the C drive to the new drive to save space. Once I transfer the photos from the C to the D, I believe I will need to import them into light room 3 again. This is not a problem, but the question is, will I lose all my tags and have th re-tag them again? It has taken me 4 days to properly tag the photos and I'd hate to have to do it all over again?
You should not have to import anything again. The information you add to the lightroom catalong is stored in a .lrcat file, which is separate from the photography itself. If you keep the folder structure of your photos on the new drive, you can simply "retarget" the existing catalog to look for your photography in a new location.
To achieve this, follow these steps:
Lightroom should keep all the metadata for those folders associated with the photos in them. So long as you use the "Find missing folder..." feature to do so, your edits should not be lost.