Another thing that might also be an option if you just want printing you could get a
print server for about $50 or less.
Also, I didn't mention it but very similar to the Shareport option is a NAS. Lower end units run about $150, and some have a print server included, like
this one from memex that is just an enclosure, so might not work with your current external drive.
The final, and most expensive option, which also has alot more functionality than what you are asking for is the
Windows Home Server. It holds up to 4 drives, will run backups for you, be a print server, file server, media server for whatever terminal you are using. It does have the advantage of not duplicating what your router you just bought is doing.