Should I upgrade my motherboard

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thanks for any help given on my problem... I'm confused about all the different options there are in upgrading my pc

here is my mobo: http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00590499&tmp_track_link=ot_recdoc/c00609380/en_us/c00590499/loc:1&cc=us&dlc=en&lang=en&lc=en&product=1843644

my whole pc: http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00609380&tmp_task=prodinfoCategory&cc=us&dlc=en&lang=en&lc=en&product=1843644

computer specs:
Asus P5LP-LE
PentiumD 820 (S) DC 2.8 GHz
GeForce 7300LE
HP LCD screen 60 hrz refresh rate 1280 x 1024
RAM (2 x 1GB) Micron PC2-4300 (266 MHz)
windows 7 32 bit

my goal is to get a new graphics card, a geforce gt 240: http://www.newegg.com/Product/Product.aspx?Item=N82E16814133321

but it is 2.0 and as my mobo states i have pci-e 1.0, i know they are backwards compatible but not all of them are, would mine work?

secondly if it would not work I would need to look for a mobo that has: socket 775 (and supports my current pentium D, i will upgrade that later), pci-e 2.0, micro atx.... after searching through newegg I see only a couple mobos that fit this....


http://www.newegg.com/Product/Product.aspx?Item=N82E16813121419
http://www.newegg.com/Product/Product.aspx?Item=N82E16813121417
http://www.newegg.com/Product/Product.aspx?Item=N82E16813121391

now which one of those will support my current Pentium D 820 smith-field but allow me to upgrade later to a dual or quad core? also if none of them do are there any other boards that are still being sold with these requirements?

 

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or is should i get a mobo that has 1.1 pci-e? has there been any problems with the gt 240 in 1.0a boards?