If its really 6 years old it cant be a P4 2.4 Ghz..because 6 years ago only P4 1.4/1.5/1.6 socket 478 proccys were available !
By the way its really hard to find a socket 478 (socket A) now a days. Even of you fiind that the price you will be paying for SD/DDR ram would be astronomical compared to DDR2 . Not only that ..you will also be paying ridiculious price for some piece of crap outdated AGP cards.
Here is what you just might have to pay
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1.845/865 MOBO Socket A .3.5K (If you are lucky enough to find one)
2.1GB DDR1/SD RAM = 2.2-2.6K
so around 2 k left for AGP crad...you can even get a fx 5200 agp version for that money now !!!!
So the best option for you is to discard your setup and go for a new one.Because you will be paying much more to retain your current procy.
If you want everything to come under 7k here are the options for you
1.Athlon x2 4400+ 2.8k
2.Asus M2N VM DVI 2.9K
3.1GB DDR 800 1K
upgrade the graphics card later
or
Intel C2D 2180
DG31
PR mobo / Palit N73HD
1GB RAM
Apprx 7k
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And if you really wanna retain your current setup..then post a WTB thread in bazar section...you just might be lucky !