Need help choosing a UPS (battery backup)

[Hammie]

When designing UPS solutions for my customers, I need to know first and foremost their required up-time.

Honestly, that stuff that you listed is not going to pull much juice. Probably right around 200 - 250 watts.

The APC Back-ups RS 1300VA LCD can be had under $200 and will run for around 20 minutes with a 300W load.

Another option will be the Tripp Lite SMART1200LCD which will give you about the same performance for about the same price.

You can probably get away with a 900VA system and cut your cost in half ($75-90). Most 900VA systems will have about a 7-10 minute uptime. Enough time to safely shut your computer down.
I personally use and design with Tripp Lite products, but its all personal.