Check the label on your existing power supply to see that this matches it but it looks like it will meet your needs:
Amazon.co.uk User Recommendation
Setting up a new Windows computer should be no harder than it used to be (despite Microsoft's apparent determination to make everything more complicated with each new version of Windows!). I usually allow a full day to work through installing security software, printer drivers, office software, image-manipulation programs, etc, etc but, as long as I've got a decent bottle of wine open alongside me, it's usually not too painful an experience ;-)