So now that my computer is 4 years old I think its time to upgrade. I have replaced the video card, and upped the ram, but also want to increase my processor. I have an HP Media Center m7248n with a MS-7184 (AmethystM) motherboard and an AMD Athlon 64 x2 Dual Core 4200+ I Know that Hp is notoriously hard to upgrade, But any help in general, Some Kind of point in the right direction would be greatly appreciated.
HP isn't really any harder to upgrade than any other brands - you said you have already done the graphics and memory... It doesn't matter where you buy from, the CPU is always hard to upgrade!
Quite frankly, as your machine is getting a bit older, you will not be able to upgrade to a very high end CPU simply because it probably isn't compatible, and for the ones that are, you probably will not notice that much of a speed increase.
If I was you, I would look on eBay for whatever the highest CPU is that your board can take and if it is cheap, get it - otherwise, save your money up for a new computer.
I have a bunch of four to five year old machines here, I can buy a brand new Celeron system now that is 64 bit and dual core that would outperform them in every way... and the depressing thing is, they would only cost about £150 to build! When you look at it like this, Just because it is possible doesn't mean it is economical or worth it.... If I was able to upgrade for £5-£20, it may be worth considering, but I wouldn't want to spend anything serious.
although the MSI MS-7184 may take a faster CPU, you may not be able to upgrade a HP computer, unless you can change CPU frequency and multiplier in the BIOS. did you check?
HP like many other OEM's using their own BIOS for that very reason, HP would rather like to sell you a faster computer rather than let you upgrade your current model :)
OTH, given the age of your computer, at some point it doesn't make sense to invest any money into upgrades, the performance increase just doesn't pay off, there are to many other bottlenecks to be taken into consideration. if you really want to upgrade a computer you should consider building a machine yourself so you can upgrade the motherboard later but keep the case and powersupply and other components, rather than buying an OEM machine.
You might be able to replace the motherboard and CPU with something a little more modern. (You would lose the investment in the RAM, as you would need to buy something compatible with the newer board)
The issue being the layout of these OEM cases aren't always the best for after-market parts. PSU placement and drive cages can be in in the way, front-panel switches might not work without modification, etc...
I think buying/building a new computer may be your best bet.