I've recently installed eight separate Windows 7 machines in the office and one of them will be in a remote location where there is nothing but a dial-up connection. As such, while setting up each computer in the office which has a fast connection, I installed all our required programs, then visited the "Microsoft Updates" site (which installs updates for Windows, Office, and other MS programs), and I installed all updates to the current date. (This was a big help because the initial set of updates totaled about 55.) I then took the single machine out to the remote location and setup the machine. Now, at each month's "Patch Tuesday", I visit the "Microsoft Update" site in the main office, run the updates scan, then download the manual installer for each Critical Update that is listed.. The manual installer for each update can be found in the "Details" section of each update's listing or by visiting the Microsoft Security Bulletin Search page at the link below.:
http://www.microsoft.com/technet/security/current.aspx
Granted, my situation is a little different because I was able to download the first set of updates by using a fast connection, but you could install ALL of the updates without using the connection simply by downloading each one manually.. I've done it before. I takes a long time but does allow you to download each of the needed update files, copy them to a flash drive, then install them on the remote computer. In addition to taking Windows Updates on the flash drive, I also take other critical updates such as those on Adobe Reader, Flash, Java, Virus Defintions, etc.
But Bob's point is good.. If the computer is going to be offline constantly, why not simply wait till you get to a broadband connection in the future and update then?
Hope this helps.
Grif