My only experience with GEMB is a JCPenney card I haven't used in 5 years so can't answer the question about whether they'll let you convert, but as far as closing the line you received, you already took the inquiry hit so unless you have to pay fees to keep it, I would definitely not close it. If you have or are planning to have any CC balances carry from month to month, the extra CL will help with your util.
It takes a while - in my experience - for cards to go inactive for non-use. In fact, my JCPenney card showed open/inactive but went open "pays as agreed" recently when I submitted a late dispute. Not only were they kind enough to remove the baddie without much hassle, they reactivated the account. Not costing me a thing!
Carol
Jan 07: tu 498, ex 501, eq 504
Oct 07: tu 716, ex 712, eq 723
Nov 07: tu 693, ex 664, eq 672_post app frenzy