It's hard to justify a quad core rig with a blistering fast and expensive video card to surf the net, snag email, "Twitter" etc.
Netbooks are handy for surfing the web on the road due to their light weight, wireless, long batery life and low price. Mine has 160gig HDD - so I can easily store 10 ripped DVDs for when I am travelling. Add VLC and you are set. Plugs into most hotel Tvs for entertainment. they also are nice sitting on the kitchen bar to catch news stories in the mornig while drinking coffee before work. Mine can run for a good 4 hours on its battery. Plus, I have my music, photos etc. Never use my portable DVD player any more.
The newer ones get crazy battery life The Asus 1000HE gets supposedly over 9 hours battery life. And it's less than 400 bucks. Can't handle HD yet, but i bet that's coming...
I think that the days of $3000 Pc's are about over. Except for the really hard core gamers. I point to the VERY interesting Nvidia Ion platform as proof. Very low price point, low energy usage,, yet it can handle 10800p video-no problemo...plus, it can fit in the palm of your hand. Can't wait for these to hit the market. HD goodness at a 300 dollar price point.