Wow. Photoshop 6 is really old. Ps 6 was released in the summer of 2000.
I bet what you have is CS 6, which is Ps 13.
Adobe called Ps 8 Creative Suite. So Ps 9 is CS 2, Ps 10 is CS 3 ......
If so Photoshop CS 6 includes
Bridge 5, a digital asset management application.
CS 6 also includes Camera Raw - ACR or Adobe Camera Raw.
ACR is the same editing application used as Lightroom's Develop module.
Consequently, if you do have CS 6, getting LR will duplicate what you already have for digital asset management and for editing
Image database management software applications use catalogs.
Lightroom's main function is image database management using LR's Library module.
A couple of Lightroom's major limitations are that LR can only open 1 catalog at a time and can only be accessed by one computer at a time (no networking).
Many other image database management applications can open multiple catalogs and can be accessed by several computers at the same time.
If you want to learn more about digital asset management (DAM) best practices I highly recommend the inexpensive book:
The DAM Book: Digital Asset Management for Photographers