'lo people. LONG-time reader of Tom's Hardware (I believe I found this site sometime in the late 90s ), first post in the forums.
 
Looking to upgrade my laptop computer's processor in order to better enable it to play back HD video. Here's the deal...
 
Been looking around for about a week now, trying to figure out wether or not my laptop will support an upgrade to a Dothan-core Pentium M, 400 FSB, 1.7GHz or higher processor. The socket types seem to match up and the visuals I've found of the pin layout are exactly the same..
 
What concerns me is whether the motherboard/BIOS will recognize the CPU and POST. Toshiba offers nothing-much in the way of BIOS updates. There's been one, and the fixes implemented are trivial.
 
CPU-Z report lists the mainboard as an "Manufacturer: ATI" and "Model: SB400" which is actually the southbridge as far as I can tell.
 
I'm pretty sure myself that I've got everything figured out, but if I haven't, I'd like to know before I make a purchase. I guess all I'm really looking for here is a little certainty before I send some stranger on eBay any amount of money.
 
 
Here's some of the more pertinent information out of the CPU-Z .txt dump..
 
Name:
Intel Celeron M 370
 
Codename:
Dothan
 
Specification:
Intel(R) Celeron(R) M processor         1.50GHz
 
Package:
Socket 479 mPGA (platform ID = 5h)
 
CPUID:
6.D.8
 
Extended CPUID:
6.D
 
Brand ID:
18
 
Core Stepping:
C0
 
Technology:
90 nm
 
Core Speed:
1500 MHz (15.0 x 100 MHz)
 
Rated Bus speed:
400 MHz
 
Stock frequency:
1500 MHz
 
Instructions sets:
MMX, SSE, SSE2
 
Northbridge:
ATI RS400/RC400/RC410 rev. 01
 
Southbridge:
ATI SB400 rev. 00
 
Mainboard Model:
ATI SB400 (0x129 - 0x2D700)
 
DMI System Information
----------------------
 manufacturer TOSHIBA
 product  Satellite M45
 version  PSM43U-00S00F
 serial  75048896Q
 UUID  B700E3A0-EEF411D9-A70E00A0-D1227C21
 
All that said, it seems pretty clear that This CPU or one like it should drop right in and boot right up, right? Please say yes.
 
Thanks, for any answers or empathetic confusion.

In theory, it should work.  The main thing to look at is power requirements.  Anytime you upgrade a cpu, you need to be able to adjust the core voltages and multipliers.  That way the board can correctly run the cpu.  I had an acer that was upgradeable, but the bios wouldn't allow it.  It took a while, but the manuf. finally released an updated bios that allowed me to use the new cpu.  If there haven't been any bios upgrades for your system since the manufacture date of the chip, I'd avoid it for now.  
As for your HD problem, what is the manuf. of your gpu?  I have an nvidia chip in my laptop, and it handles the HD.  It may be you can get a performance boost in playback by updating the drivers for your chipset.  Also, look for a low-level player, something that takes up minimal system requirements.  I recommend VLC Player, but there are others out there.
If you do the swap and it works, keep an eye on your temps! If it doesn't, well, there's always ebay!
Good Luck!

Power requirements seem to be equal.
 
Only way to adjust the voltage on this board is to drop a copper wire into the CPU socket. lol.
 
Not counting on Toshiba to release any more BIOS upgrades.
 
Manufacturer of the GPU is AMD/ATI, but I'm entirely certain the CPU is the bottleneck on HD video.
 
Have the latest drivers for the GPU/video chipset.
 
Using Zoom Player Standard, my latest favorite.
 
Hopefully I won't have to re-list this CPU when it gets here. Purchased a seemingly very rare SL8U6 (Pentium 4 M, Dothan Core, 1.8GHz).
 
Model number                             745
Part number                                RH80536GC0332M
RH80536GC0332M s-specs         SL8U6
Frequency (MHz)                         1800
Bus speed (MHz)                         400
Clock multiplier                            18
Package                                      478-pin micro FC-PGA
                                                   1.38" x 1.38" (3.5 cm x 3.5 cm)
Socket Socket                             mPGA479M
Introduction date                       May 10, 2004
Price at introduction                   $423
 
Crossing my fingers.    
 
Thanks for the reply.