Trying to pick surge protector or UPS, a little confused

So I'm thinking of buying a surge protector or a UPS, but many of either are rated by "VA" rather than Watts. I understand that VA is how much power it could supply with no resistance, but I'm a little confused as to how I can convert this to watts seeing as I have no idea how much resistance there would be between the surge protector/UPS and my power supply.

Can anyone help me figure out what kind of VA rating I would need? My PSU is rated at 850W (assume roughly 950W pulled under max load).