CPU Replacement dimension 4600, 2400 and graphics card

im a noob but im not too awful.  and i know its not worth it but im going to do it anyway. I have made several posts about a dell dimension 2400 and a dimension 4600 that i am currently pumping some more juice into.  I know the general consensus is get a new system.  these 2 computers are for single designated tasks.  the 2400  currently with 2.53 and 2 gigs sp3 xp home.  which  I sped up for my mom to use for email  I keep my new downloads of music and movies organized and light gaming SNES NES N64 genesis roms .   and the 4600 with xp pro 2.8  4gigs sp3 i would  hope to get little more out of  to run some pc games from the mid 2000's playstation 2 emulators dreamcast 128 bit what my question is.   A.  is it worth it to get a graphics card for both of these computers so they have a dvi input as do my monitors, and also . I picked up 2 3.0 processers off ebay for 12 bux.  how hard is the install .   I have another 4600 laying around i try to learn from.  it seems as if i just  pry off the heat sink on both models being that they are basically the same internally with regards to the processor being under the heat sink.  I know i need to clean the processors. how do i do this. and and apply the thermal compound i need to purchase. is it like installing ram.  take out replace and boot or is there more to it.  other than cleaning the processor reapplying the thermal compound and booting. And honestly sine i am a noob  Is there a serious risk i will blow out these computers becasue ive had them so long it would be a shame  just to run some apps a little faster I would also like to know what the max CPU's these PC's can take.  i only want to do this if it is simple like a ram upgrade but i am totaly confidant with everything on both of these motherboards and disassembling a heat sink and getting to the processor and removing its the replacing cleaning thermal compound reboot.  i know its alot to take in.  but i love learning  on these disposable PC's which really arent that disposable if maintained :)

 DecadeOfDell

I have another 4600 laying around i try to learn from.

 A. is it worth it to get a graphics card for both of these computers so they have a dvi input as do my monitors.

Yes.

 I picked up 2 3.0 processers off ebay for 12 bux. how hard is the install .

The procedures for replacing the dimension 4600 processor, is HERE

Directions for cleaning and applying thermal compound, are HERE.

You only need a small tube of thermal compound, this can be purchased from any computer store.

When removing and reinstalling the processor, make certain the pins are not damaged or bent.

 i only want to do this if it is simple like a ram upgrade.

No, it's not as easy as upgrading the memory.

 I would also like to know what the max CPU's these PC's can take

The 4600 support's Socket 478, P4 533/800 MHz FSB processors.
The early 4600 models will take up to 3.0GHz and the later models, to 3.2GHz or 3.4GHz, this does not offer much of a boost over the 3.0GHz

Prior to installing the processor, check that BIOS version A12, that has added support for newer processors, is installed.

Bev.