Here is a handy chart to the wattage you need:
PSU REQUIREMENTS - RealHardTechX
www.realhardtechx.com
I might suggest more than 550w.
Modern graphics cards like the 3000 series can have high power spikes and a stronger psu can cope better.
In time your most logical upgrade will be to a stronger graphics card.
I might buy the 650/750 or even 850w .
The incremental cost of higher capacity is usually not great.
A psu will only consume the power demanded of it, regardless of the max capacity.
And, you are wise to be looking at a quality psu with a 7 year warranty.