question about ups voltage for backup power supply

i have chosen the APC BE650R 650 VA 390 Watts 8
Outlets UPS for my computer.

http://www.newegg.com/Product/Product.asp?item=N82E1684...

my comp has a 700w psu, and i expect it will routinely
be in 500-550w area for power use.

my purpose with the apc is only to serve as short
lived backup power for a few mins max in case the
power goes out, and to protect from surges and spikes.
i do not intend to use it for any sort of sustained
power.

i had someone tell me that the APC BE650R 650 VA 390
Watts 8 Outlets UPS i am considering will not be
sufficient. in his words: " When you try to draw too
much power from a battery backup unit, it'll trip the
circuit breakers (or melt some leads) in the backup
unit."

my intention in buying the apc is only to give myself
a min or two of power in the event of a power outage
in the house, so that i can shut my system off, and
also to protect again power spikes or surges. the
price of apc ups's above 390 watts get pretty
high--btwn $150-450, which is pretty steep.

is his advice accurate, and should i pony up for the
higher wattage units?

someone at tom's hardware forums countered that
earlier response, claiming:


"That UPS won't give you a lot of up time, but it is
fine for protecting against short (1-2 minute) outages
and it definitely won't melt down or anything crazy.
Sounds to me like it meets your planned need. "


so, before i order, i need to know- which is it?

thanks

here are my specs (lite on sata drive not included since newegg doesn't have it):



LIAN LI PC-7B plus II Black Aluminum ATX Mid Tower Computer Case - Retail

Seagate Barracuda 7200.10 ST3320620AS (Perpendicular Recording Technology) 320GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM

eVGA 768-P2-N831-AR GeForce 8800GTX 768MB GDDR3 PCI Express x16 HDCP Video Card - Retail

Creative Sound Blaster X-Fi XtremeGamer 70SB073A00000 7.1 Channels PCI Interface Sound Card - Retail

OCZ GameXStream OCZ700GXSSLI ATX12V 700W Power Supply - Retail

APC BE650R 650 VA 390 Watts UPS - Retail

CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400 - Retail

EVGA 122-CK-NF68-AR LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard - Retail

Intel Core 2 Duo E6600 Conroe 2.4GHz LGA 775 Processor Model BX80557E6600 - Retail