Question about installing a new hard drive.

I was hoping to upgrade the 80gb hard drive on my macbook now, to the maximum it can hold (500gb). I hear good things about the Western Digital Scorpio Blue, so I was going to go with that one if it was recommended.
I have a white macbook, pre-unibody, 2.0 GHz Intel core 2 duo, 2.5 Gb ram, running OSX 10.5. As much as I would love a shiny new macbook pro, I can't afford one and it's way cheaper to upgrade the hard drive and os.
I know I need to format the hard drive for mac once I buy it, but my question is that can I buy the snow leopard discs and use the disk utility on the snow leopard discs, so that the new hard drive will just install snow leopard straight away? If what I'm saying makes any sense lol
Basically I would like my new hard drive to run snow leopard straight away. Which is possible, yes?

The answer is yes. Once the new hard drive is installed, boot with the Snow Leopard DVD, run Disk Utility and format the new hard drive. Then use your Time Machine backup to migrate everything over. You do have a good Time Machine backup, right?

Thanks! But no I never used Time machine, although I have an external drive to transfer things I can't do without. Should I set up a time machine just in case? I don't have any important documents or anything, but will it save applications so I don't have to reinstall everything?

I used freeware called Carbon Copy Cloner and it copied everything, including the OS and then put it all back on the new HD hassle free.

As the previous reply stated, you could use Carbon Copy Cloner (which by the way is not freeware, author requests donations.) but the best way is to use Time Machine. CCC leaves fragmentation while Time Machine does not.