I have a dual core running at 1.83Mhz (stock) and a 8800GTS card. I use ESET Nod32 on windows vista and my machine runs nice and fluid. I've tried others and so far, the Nod32 software has worked the best for me.
The core duo is IMO, the best out there right now. Dell just slashed prices on this one and is a great buy. Yes, it's a dell. They do make very good laptops.
http://www.dailytech.com/article.aspx?newsid=2073