I have intel celeron 2.66ghz. is it ok to upgrade my Memory(using DDR2) into 1GB?

Intel E219882 motherboard, also know as Intel D850GB?

No.
1) The motherboard has a Socket 423 processor socket.

http://en.wikipedia.org/wiki/Socket_423

This processor socket has the socket holes, while the processor has the pins. Has 423 socket holes.

The Intel Celeron D 315 uses an LGA775 processor socket.
LGA775 is also known as Socket T. Has 775 pins in the processor socket. The processor used has the socket holes. 775 of them.

Celeron D 315 spec's,

http://en.wikipedia.org/wiki/List_of_Intel_Celeron_microprocessors#Celeron_D

2) The Intel D850GB motherboard only supports Single Core processors. Not Dual Core like a Pentium D.
Must be an Intel single core processor, that fits in a Socket 423 processor socket.

Intel only made processors to fit the Socket 423 for about 2 years. Intel had a deal with Rambus, for memory to fit Intel's motherboards, for this period of time. The deal fell out, and Intel moved on.

The Intel D850GB motherboard Only uses RIMM memory modules, ('Stick/s') made by Rambus.
(RIMM. Rambus Inline memory Module)

Highly expensive, overrated ram memory.

Intel D850GB motherboard specifications,

http://www.intel.com/support/motherboards/desktop/d850gb/sb/cs-013247.htm

On this page go down to -
Product Specifications [PDF]
in blue, and left-click on it.

After you click it may take a few seconds for the PDF file to show.

Sorry to be a bummer, but wanted to give you in-depth info about your motherboard.
Have any additional questions, please state so in a Comment.

You should be able to upgrade the CPU, since it seems that the DV1000's motherboard uses a socket CPU design. But, obviously, HP would rather have you choose the CPU that you want from the beginning and stick with it.
The first thing to do is to check HP website to see what other configurations were/are sold for your model. If they sell it with faster CPUs then you can upgrade to one of them...

PLEASE NOTE:
In order for a particular processor to be compatible with a particular laptop:
(1) the processor must be physically compatible with the laptop socket, in your case I thing you have a Soket 479 processor
(2) the laptop chipset must support the processor.
(3) the chipset front side bus speed must match the processor front side bus speed, in your case 400Mhz.
(4) the laptop BIOS must support the processor.

So I listed here processors with FSB at 400Mhz, I gues that DV1000 as a 855GM Motherboard that supports only 400Mhz with Socket 479

Pentium M

Banias
Pentium M 1.3 1300 1024 400
Pentium M 1.4 1400 1024 400
Pentium M 1.5 1500 1024 400
Pentium M 1.6 1600 1024 400
Pentium M 1.7 1700 1024 400

Dothan
Pentium M 710 1400 2048 400
Pentium M 715 1500 2048 400
Pentium M 725 1600 2048 400
Pentium M 735 1700 2048 400
Pentium M 745 1800 2048 400
Pentium M 755 2000 2048 400
Pentium M 765 2100 2048 400

Celeron M

Banias-512
Celeron M 310 1200 512 400
Celeron M 320 1300 512 400
Celeron M 330 1400 512 400
Celeron M 340 1500 512 400

Dothan-512
Celeron 205 1200 512 400

Dothan-1024
Celeron M 350 1300 1024 400
Celeron M 360 1400 1024 400
Celeron M 370 1500 1024 400
Celeron M 380 1600 1024 400
Celeron M 390 1700 1024 400

Best Regards

Head on over to crucial.com and use their "crucial system scanner tool."
It will detect the type of memory that is compatible with your system,and it will also suggest the max amount of RAM or memory you can upgrade to.  Their prices are decent as well.

absolutely

If your video card uses a portion of your system RAM you can adjust the amount it uses through the BIOS or the advanced settings of the Driver Software.

Typically, the amount of video memory is locked because it's integrated to the video card; the only way to upgrade the card capabilities is by upgrading the card itself.

If you have an Integrated Intel Graphics Accelerator follow these links:

http://support.intel.com/support/graphics/detect.htm?iid=business+download_gmav

http://www.intel.com/support/graphics/sb/CS-029090.htm

http://www.intel.com/support/graphics/sb/CS-003999.htm

it is better to use intel core2 dueo or intel quad core processor

I alot of cases, yes you would notice the effects becuase of the L2 Memory change, Celeron's are a cutdown verison CPU to save them money.

here are the specifications of *********** board go through it...
Processor Support Intel® Pentium® 4 processor, Intel® Celeron® D processor and Intel® Celeron® processor in the 478-pin package
Note: It is important to verify supported processors before using this Intel® desktop board. Supported front side bus speed 800, 533, and 400 MHz Integrated Graphics Intel® 865G Chipset with Intel® Extreme Graphics 2 Chipset Intel® 865G Chipset AGP Connector AGP 3.0 (4X & 8X Speed 1.5 and 0.8 Volt Only) Memory Type Dual Channel DDR 400 MHz (PC3200), 333 MHz (PC2700), and 266 MHz (PC2100).
Note: Be sure to review important memory and system bus speed considerations before using this Intel® Desktop Board Max Memory Capacity of up to 4 GB Memory Slots 4 DDR DIMM Sockets Slots 6 PCI
So it will support DDR2 and you can upgrade upto 4GB...

yeah!! you can do an upgrade as long you know the specifications of your system unit. its ok..it seems that your'e good to go improve the performance ( just don't exceed it to 1GB ot it will crash your motherboard)

Goodluck!!! Have Fun!!

With notebook there are not many upgrades available, but if you are using a lot of multi-media it is savvy to increase you memory.

My suggestion is that you look to go up to 2 Gb; you should see a nice different on performances.

 

See the link here below as a reference from Toshiba