major big diff between the celeron and the P4
P4 is much faster, but faster = heat and shorter battery life...
P4 Mobile is a little better, but not much.
You might want to look at the new Centrino chips. Built in wireless, lower voltage and great battery lifes. Not the power of the P4HT but much much better than Celeron. If batt life is important to you, Centrino is the ticket!
Celeron is fine for what you describe, I have used a Celeron notebook - but its not worth the 100-200 difference. It works, but thats about it...I suggest NOT buying the Celeron. Celeron notes are lower end, and come with low-end integrated video, etc.. and become outdated quick.
Me personally, I like the P4 desktop chip in notebooks - but I plug in anywhere I go and I take care to keep dust out of it to prevent heat (slows you down)...I have a 2.8Ghz P4 note with 1 gig ram and its just like a desktop..fast. You can move files or download neked chik movies at lightnin' speed!!! (if thats your thing)
Look for a brand name with P4, P4mobile, or the Centrino - 15 inch SXGA screen, and go for a LEAST 512mb RAM with Windows XP.....
you should be able to do this for 1000-1300 bucks at Dell or Compaq. I personally like IBM but they are pricy. Have had all 3 mentioned and never a problem with ANY. Hard to beat Dell for the price. You may hear complaints about Dell, but thats simply b/c they sell 5X the computers anyone else does...
PS - Laptops will always seem slower b/c most come with slow hard drives..4200 rpm..if you really want speed, you have to get a fast hard drive -- no matter what chip you decide!! -- but again, this gets the price up a few hundred bucks...so we could be getting carried away here..
good luck!