Old 24" iMac Upgrade Possibilities?

[colorspace]

I was thinking of buying an older 24" iMac (2006 C2D) and upgrading the CPU, HD and RAM. But I have a few Qs:

1. What is the fastest CPU that I could drop into this iMac?

2. I know that you could put 4GB or RAM on this machine, but it only sees 3GB, is this a limitation of the MB or CPU?

3. Finally will most SATA HD work in these systems?

Thanks in advance for any info, especially from those of you that may have tried this in the past.

 

[flopticalcube]

1. 2.33GHz Core 2 Duo
2. Motherboard
3. Yes. Sata II

 

[colorspace]

Would the older Core Duo iMac systems, if upgraded to a C2D, also be able to access 3GB of RAM?

Thanks

 

[colorspace]

Anyone on my last Q - this would make my iMac possibly worth upgrading (it's a CD not C2D). Along with that question I guess I'd also like to know if with a C2D CPU my machine would also be 64-bit as far as 10.5 is concerned.