There are various firms that do this, but if you still have (or can borrow) a reel-to-reel player that has a usable output it shouldn't be too difficult to do it yourself, or to find a friend that can. (Same principle as converting vinyl to CD: feed a suitable output into your PC and use Audacity or similar to record, then burn with Nero/Roxio or similar).
I haven't used any of these services, and these are just from the first page of a Google search for "reel to reel to cd transfer" - there are more that may be cheaper/better: