elemein,
If you have a P4 /Socket 775 on a Dell or HP, you won't be able to overclock the Pentium 4 3.0.
However, you can buy a P4 670 @ 3.8 GHz for about $25-30 and which will be 64-bit and hyperthreading= appear as 2 cores. I've seen a 3.6 P4 660 for as little as $10-15.
My 4th level computer is a Dell dimension 8400 from 2004 ($1,800) with a P4 630 @ 3.0Ghz. 3GB RAM (max 4GB), Quadro FX 570, 256MB PCIe, 750GB Seagate. Running XP Pro 64-bit with AutoCad 2004 and AutoCad R14 (1998), Adobe CS3, Sketchup 8 Pro, Corel Graphics Suite X4, Word Perfect 12, and MS Office Business 2003. What's amazing is that when running applications from the time of the computer as I do, it's really quite fast. Except for a few tasks such as rendering, most applications even today are single threaded- even Autodesk Inventor 2013- and therefore the clock speed can be very relevant. Even the old grpahics cards are not dustbin material- if you look at the Autodesk site, the Quadro FX 570 is still a certified card for AutoCad 2013 which has extensive 3D capabilities.
So , no overclocking, but with the right software these ancient crocks and the 670 64-bit hyperthreading can still be quite useful even in demanding photo editing, HD recording- I made 100's of CD's of live recordings on the 8400 as recently as 2011 (when I bought an HP Elite m9436f QC Q6660 3.4GHz), using an M-audio 2496 card with Cakewalk Home Studio 2 XL.
I think the old bangers are fun to get going as fast as possible- and if you stay with the programs of the time- for example Corel GS 12 is 1/5 the size of Corel Technical Designer X5 I use now- it works just fine.
My 5th computer is a 1998 Dell Dimension XPS T700R ($2,100) PIII 750MHz, 768MB RAM (max), Radeon 9200 126MB AGP, Ultra 66 SCSI controller with 30 GB and 80GB HD's. This is running XP Pro 32 bit, with AutoCad R14 (1998), Corel Graphics Suite 7, WordPerfect 8, MS Office Pro 1995. Again, not a screamer in 3D, but it's not embarrassingly slow even then and when running programs from the last Century, there's not much waiting.
I'm not a unique eccentric in this. I know a professional freelance drafting consultant using a Dell Dimension 4400 P4 (2002) @ 1.6GHz, 128MB AGP graphics card, an 80GB internal IDE and 3 or 4 external USB drives, Win7, running ArchiCad 15 - a $4,500 3D CAD program that has an internal rendering program, Photoshop and Illustrator and more. I offered to give him the Dimension 8400, but he was "doing just fine" with the 4400 and he didn't want to take the time to load and configure everything. Final story- a friend who is an energy consultant in CA, uses an HP 386 at 25MHz ! from about 1992-3 to run Title 24 building energy simulation reports. That computer replaced an Apple II ((1986?)$8,500?) without HD's- everything ran off 5.25" floppies on external drives. HP was an early 386, the cutting edge then and cost I think over $6,000. He can't get drives for it- pre-IDE- and he made a wood HD mount for an IDE that runs to some kind of PCI IDE HD controller.
We've come a long, long way in the faster and cheaper, but don't give up on the surprisingly useful- and next to free- antiques!
Cheers,
BambiBoom
HP Elite m9426f (2010)
Dell Precision T5400 (2009)
Dell Optiplex 740 (2006)
Dell Dimension 8400 (2004)
Dell Dimension XPS 700R (1998)