Hi
DialerIve been using Site Advisor for almost a year and its one of the most fantastic things Ive ever had for my browsers

McAfee Site Advisor is
very effective in IE7 and on Vista (as I am not a vista user I dont know this first hand but ive heard good things

)
It is very light on your system (you will forget its there after a while thats how light

And it doesnt use hardly any bandwidth (if it does it isnt noticible and Im on dial up too is thats how I know

)
Dont worry about the Site Advisor pages loading slowly. I get this too

.
I highly recommend site advisor. But it would be nice if it could be used for opera.
Happy surfing and good luck with Site Advisor if you choose to use it :D