How Do I Choose The Hard Drive Capacity For A New Computer?

Couple of things first of all to clear up some confusion that is evident here.

Gigabytes are a method of measurement for memory size. They can be a reference to RAM, or hard drive size. This is, however, not all you will need to consider in this. You will also need to think about the speed of the computer. How fast do you need this machine to be? For an average classroom machine to be used only by the teacher, assuming that teacher is not in computer science (which seems unlikely in this case) and the computer will be used for presentations, documents, and so forth, a fairly modest computer would more than likely be adequate. Here are some suggested specifications:

AMD Sempron 2800 or Intel Celeron 2.8GHz
512MB RAM
80GB Hard Drive
Windows XP

If you intend to run Windows Vista, the specifications would be slightly higher:

AMD Sempron 3200 or Intel Celeron 3.6GHz
1GB RAM
160GB Hard Drive
Windows Vista

Hope this is useful.

I think you need at least 1GB Ram and 250GB hard disk because the prices between the specification I gave and the other guy's specification are similar. Think about it