Dell Inspiron 1720 Upgrade

Just registered so this is my first thread/post.

I have a Dell Inspiron 1720, which is well out of warranty and I am looking to do some DIY upgrades.

My current spec is:

Windows 7 - 32-bit

Intel Core 2 Duo T5750 @ 2.00GHz
3 GB RAM
Samsung HM320JI ATA Drive - 320GB @ 5400rpm
NVIDIA 8400M GS GPU

I am looking to upgrade:

CPU - Intel T9300
HD - Seagate Momentus XT 500GB Hybrid
GPU - NVIDIA 8600M GT

I have been trawling through the internet and this seems to be the best I am going to get out of the Inspiron 1720.

Has anyone else performed these or similar upgrades on the Inspiron 1720? Do you have any advice on how to carry out the work etc?

Cheers,

Warren