you can parse country information from whois response. the various ip authorities have different record formats so you have some work ahead of you.

ARIN will tell you if you need to go to another authority. Look for the Referral Server field. The presence of this field indicates that the record is delegated.

Also look for and follow referral records to the final netblock record. if you get a record with nothing but netblocks, the smallest netblock is the one you need to search for the whois record on to get the information. These referral records are created by ISP's who sublet chunks of their IP allocation.

If you aren't familiar with text parsing and especially IP address calculations, working with whois, and need to do this in a hurry, I'd buy the database. It's a *lot* easier. They have a trial database so you can demo it. Just make sure you use IP's in the trial database for demo.