Dominick_1 :
couse i have it and it still works for my needs
Dominick_1
It's a lot of work to change a motherboard and for the Dimension 2400. the CPU, RAM, a video card will have to be added also- you can't reuse anything except the case and power supply. My suggestion is to set a budget and buy a Dell Optiplex 760 or other system that may use DDR2 RAM and a PCIe graphics card. You can do a lot with $100 or so.
If however you like the style of that era, you might fit a Dimension 8400 motherboard- at least the case looks to be the same. The 8400 can use a hyperthreading, 64-bit Pentium 4 up to 3.8GHz, and has a PCIe video card slot. I have a 2004 Dimension 8400 and ran it with Windows 7 Ultimate 64-bit, AutoCad 2007 and Adobe CS4 and it did surprisingly well. See:
https://www.dropbox.com/s/tzsvx1cbxs00res/Dimension%208400_Front%20R_%20cpu_12.13.12..jpg?dl=0
However, I see that a Dimension 8400 motherboard will cost a least $30-40, the CPU is $15, the RAM is whatever, so it might add up to more than just buying a working 8400 or one the other, newer systems mentioned.
Overall, I'd say the easiest method, and best use of effort and cost would be to buy a newer system.
If you only reply every 5 months, I'll be watching in July.
Cheers,
BambiBoom