Recommended light tablet laptop for a college student?

What tablet would you recommend for me?
I already have a inspiron e1505, which I'm going to plan to use at home.
I want a tablet pc thats very light and pretty fast, so I can take notes in class.
I'm mostly on campus all day and so I'll have a chance to recharge my laptop.

I've been looking into the Lenovo ThinkPad X61s
I've customized my own so far and the specs are...

Intel® Core™ 2 Duo L7500 LV (1.6GHz, 4MB L2, 800MHz FSB)1
Genuine Windows Vista Home Basic12
12.1" UltraLight XGA TFT, 2x3 UltraConnect II antenna
4 GB PC2-5300 DDR2 SDRAM 667MHz SODIMM Memory (2 DIMM)8
TrackPoint
120GB Hard Disk Drive, 5400rpm Serial ATA (2.5")4
No Bluetooth
Intel PRO/Wireless 3945ABG10
ThinkPad X61s 4 Cell Enhanced Capacity Battery60
7668: Express - 1 Year Depot Warranty7
Which is about $1,534.00 and weighs about 3.5 lbs

I'm also looking into the HP tx2500z series
Genuine Windows Vista Home Premium with Service Pack 1 (32-bit)
AMD Turion(TM) X2 Dual-Core Mobile Processor RM-70 (2.0GHz)
Display12.1" diagonal WXGA High-Definition HP BrightView Widescreen (1280 x 800) w/Integrated Touch-screen
4GB DDR2 System Memory (2 Dimm)edit
ATI Radeon(TM) HD 3200 Graphics
160GB 5400RPM SATA Hard Drive
PersonalizationWebcam Only with HP Imprint Finish (Echo) Wireless-G Card with Bluetooth
SuperMulti 8X DVD+/-R/RW with Double Layer Support
6 Cell Lithium Ion Battery
Windows Vista Ultimate (64-bit)
This is a lot cheaper at $998.98 but is about 5 lbs...

Do you think the Lenovo thinkpad is worth the extra $$?
I just want a really light and functional laptop for my classes.
(I wear totebags and so I was just wondering whether 5 lbs is too heavy to be carrying around all day..)

Thank you so much!