Some PCs slow domain network, some fast. What to look for?

Hello all,

We moved office and onto a new (larger corporate) windows domain. But

a bunch of our computers are very slow to transfer files around

between PCs (someone noted they are all slightly older Dells), while

others are lightning fast.

What are some of the things I should look for in determining what the

issue could be here? Any help would be greatly appreciated.

Thanks!

DeanB