We bought this to protect our PC running Windows 7 (64bit)and were previously using Norton but have experience of using Kaspersky and Panda security.
Installation was a breeze on our PC, although, interestingly we had a few days remaining on our existing Norton licence but only got 365 days coverage on installing this - so no credit for the unused days!
Norton Internet Security has, in the last couple of years been refined considerably. It exerts far less strain on the system than it used to, as, at one time, it threatened to overwhelm more lowly computers. Both programmes updated quickly over broadband, and, once set up do so automatically without trouble. I think Norton have invested in making the interfaces as intuitive as possible. The Internet Security interface is easy to understand, although, the gadget it puts on the Windows sidebar seems to incorporate a whole load of features that you won't access very often - such as Mobile Security; Norton Management; Norton Parental Control etc. - I can't see any way of customising this panel. Otherwise it's a case of setup and leave it - probably until the next renewal. You'll hardly know it's there! There are sites you can visit to test the efficacy of the protection it affords and Norton benchmarks very well indeed.
In summary, vital protection for your PC, good value, intuitive to configure and keeps your PC safe. Recommended.