The process is a known as a repair installation. The repair installation will leave your programs/settings intact, but you will need to reinstall any/all service packs and/or updates.
As Ru1 suggested, you CAN back up your wpa.dbl and wpa.bak file (really, only the first is important), run the repair process, then replace those files to avoid activation. This ONLY works after a repair process. It does not work if you format your drive and reinstall from scratch (and make certain you use the same cd-key used in the original install).
It is a common misconception that you can back up your wpa.* files and replace them to circumvent activation after a full format, but this is NOT correct. This is based on the false notion that your activation is tied to your hardware (only). There is more involved, so installing windows from scratch will necessitate the need to reactivate.
BTW, it is 30 days for reactivation.
To recap, back up you wpa.dbl and wpa.bak file (should be in c:\windows\system32)
Perform a repair installation
(here is a good link to follow)http://www.michaelstevenstech.com/XPrepairinstall.htm
After installation, reboot into safe mode, copy the previously saved wpa.dbl and wpa.bak to c:\windows\system32)
You should be able to continue without activation (but your windows updates will need to be reapplied).
Since you lack a good internet connection, see if someone can download a copy of autopatcherxp and burn it a cd for you. (as well as atleast sp1--get the corporate download)
Here is autopatcher xp, a compilation of windows updates (plus other goodies)http://www.autopatcher.com/