I did a clean reinstall of ubuntu moving up to 10.4 (I wanted the gnu interface not the one that comes with 11.10.)

I got some vague message about wifi that I could not make sense of during the install.

I did a reinstallation of my data files, preference, bookmarks, etc.etc.etc. and have been getting everything working just right using the laptop at home very successfully for a couple of weeks now.

Today I took it to the public library and tested the wi-fi.
!!!!! NO WIFI !!!!!!

I think what happened is that I had the hardware switch that shuts off wi-fi in the off positon during the install and the install could probably not find any wifi on the computer, and did not set it up.

---------- question ----------
How can I get the wifi up and running WITHOUT redoing all the install work I have already done.
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I only use wi-fi on this machine when I am traveling but I do need it then.

Hardware:
Dell Studio 1535 laptop.