i want to upgrade but not spend so much, possible to buy new processor and mother board and would it fit in any pc case or does it have to be specific?

There are two main form factors when it comes to custom-built IBM-Compatible PCs. A form factor is simply the specifications for the physical size of the motherboard and the layout for the chip set and various components:

Advanced Technology (AT) Form Factor:

Developed by IBM in 1984. Was the first form factor for motherboard. Subsequent motherboard design advances have made current AT motherboards much more advanced than the original AT board. AT boards are pretty hard to find now.

Baby Advanced Technology (babyAT) Form Factor:

Smaller more streamlined version of the original AT form factor. Again, you will have problems finding these.

Advanced Technology Extension (ATX) Form Factor:

Developed by Intel in 1995 this is the most commonly used motherboard in current custom built computers. Can support all new processors. CPU is placed next to power supply unit.

Micro Advanced Technology Extension (microATX) Form Factor:

Small version of the ATX form factor. Is backward compatible with ATX.

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When you are looking to upgrade your motherboard and/or CPU make sure that the motherboard form factor you are going to purchase is compatible with the case you have or plan on buying. An AT motherboard will not fit into an ATX-designed case (the riser pins do not match up). Another problem you may enounter if you have an older case with a newer motherboard is that your power supply unit may not supply the relatively newer 4-pin supplemental power supply cable. This means you will have to buy a new case with a power supply or a new power supply. Another important factor to consider is that certain motherboards will not accept certain processor types. The biggest distinction you can make is to whether the board supports Intel or AMD processors. Intel uses a wide variety of sockets or slots for their processors while AMD generally uses Socket A and Slot A (AMD Athlon XP processors use the Socket A). In short your motherboard will need a case designed for its form factor and your CPU will need a motherboard with the proper type of socket/slot to fit in to.

ok Thanks for info,

lets say i buy all that stuff,
the harddrive i have, 40 gigs of memory,

its a general question but just answer like above if possible
could a hard drive connect to anything?

thanks

Your hard disk drive (HDD) fill fit into whatever form factor case you decide to buy as long as it has a standard 3 1/2" drive bay. Anything with a floppy disk drive (FDD) has one.

well you can fit a HD into a %.somthing drive bay that you use for CD drives if the is one free.