Don't qoute me on this but I believe OEM simply means the product doesn't come wiht the retail box, manuals, or warranty. If it were be I wouldn't go with OEM becuase for a little more money you get the manuals, and the security of your product being backed by a warranty. For example, An OEM AMD 3400 proccessor is 404$ while a regular one is 416$. IMO it's worth the extra. Keep posting if you have any more questions!
OEM if it breaks you gotta buy a new one full price...
Retail you usually get a year warranty and manuals and for processors usually a fan and heatsink, OEM would just be the processor no fan/heatsink/paste
IT IS WORTH IT TO GET RETAIL!
There's nothing wrong with buying OEM if its not so expensive parts like the sound-card etc. I myself am using OEM parts in my pc and not faced any problem so far. However it it safer to get retail parts like processor and graphics card as these parts are costly and not worth the risk.
I'd like to add one more comment,oem hard drives,cd-rw's and dvd are fine if you don't need the software packaged,and any driver disks these plug and play days,
right guys ?
The websites will tell you the diff.