1) Yes, it's all in the marketing, Centrino is a nicer sounding name than Celeron with Wireless...

2) Get a 15" or 16" with a UXGA screen (1600*1200) resolution, many widescreens only do 1280 x 854 or even 1280 x 800. That is much too low for power-use. In the end resolution will give you more desktop for your buck than screensize.

If money isn't an issue then look at the Sony Vaio GRT series where $4000 will get you 16.1" UXGA, 2.4GHz Mobile P4, 1Gb or ram and an 80Gb drive PLUS a DVD+/-RW drive.

Another EXCELLENT pick is the Toshiba Satellite P25 with Windows Media Center. Also has a DVD burner AND TV-tuner build in with a 17" widescreen. Their top model P25-S607 will run you around $2690.

Intel® Pentium 4® Processorª with Hyper-Threading Technology
Microsoft® Windows Media Center Edition,

17.0" diagonal Wide-Screen XGA display* (1400 x 900)
NVIDIA® GeForce™ FX Go5200 GPU w/32MB DDR SDRAM (64MB on P25-S607 only)
60GB¹ hard drive
DVD-R/RW or DVD Multi Drive (P25-S607 only)
harman/kardon® stereo speakers
Integrated Wi-Fi™ (802.11a/b)