Question : Problem: Purchasing UPS.  Need help calculating what VA capacity.

I am looking for 30 minutes runtime with the following specs on the electronic equipment:
120 V AC
8.0 A  750 VA

What VA capacity UPS should I purchase?

Answer : Problem: Purchasing UPS.  Need help calculating what VA capacity.

A UPS calculator would be a good tool to start with. Here is one from APC.
http://www.apc.com/tools/ups_selector/pso/OnSale/