I am looking for opinions on whether or not to stick with retail or OEM/open box parts. Please post your opiniond, Thanks.

Retail or OEM has it's differences sometimes, sometimes not. For example:
 
OEM Hard Disks will fail more frequently than the retail ones. That's why the warranty time is shorter (a lot shorter).
 
OEM processors come without heatsink or fan. Also, sometimes the better chips will go retail, so a retail chip usually will overclock higher and with better temps than an OEM processor. Warranty: OEM 90 days, retail 3 years.
 
OEM Vista: can be installed with 1 computer and will "marry" that computer for good. If you upgrade your motherboard the system is gone. The retail Vista can be installed multiple times in multiple PCs (one at the time of course).
 
Open Box is another thing. They are (usually) retail parts that had any problem with them (returns, package defects, etc), but they are the same part as a "close" box. So you can make a good deal with open box parts if you get 'em from a reputable seller.

Yes to oem, no to openbox.

open box can come pre-broken with no warranty, OEM at least Have to work (for me, i would just get retail for safety)

It would matter to what OEM part your asking.

I've brought an OEM HD, and have had no problems.

I've brought an OEM MB, and have had no problems.  Now the thing about this purchase I did, it was bare bone.  I only got the MB in the anti-static bag.  It didn't even come in a box of its own.  That might be the last time I ever do that again.  

I've even brought 2 OEM CPU's, considering a 3rd perhaps later on.. and the 2 that I have, are still working.  I usually buy a 3rd party HS, and I do have one retail, with a stock HSF that I use for a paper weight... na, I just have sitting on a shelf collecting dust.  

The only advantage in OEMs, you can get items cheaper, but yet have a higher risk of things failing.  (edit: short warranties)

Now as far as OEM OS by MS, as long as you call the number to reactivate a new installation of the OEM OS to deactivate the old, you can move to another platform or MB.  It's just MS way of making sure only one copy is running, rather then 2.

OEM OS by MS, I have swapped MB's three times since last June and MS reactivated my OS with just a few questions and about 10 minutes on the phone. I am running Vista Ultimate 64bit with the SP1 RC service pack and it's working great. Will not go back to XP.

If the MOBO's model is the same there is no problem reactivating. If you change platform then you could have problems. IE: 680 chipset replaced with P35.

Thanks for all the great replys, jammer

 
10 minutes!!?! otherwise yes - oem still can be activated with a new pc - prolly not legally but meh.
 
As for OEM hdd's - i work in a retail store and we sell ONLY oem drives - no big issues, and most come with 3+ years warranty.

OEM and retail are in fact the same parts.
HD's do not come with manual or mounting extras.
CPU's do not come with cooling units and have a much shorter warrenty.
 
I would NEVER buy an "opened box".

Lets define the terms so we all agree with what we are calling each.
 
Retail: Usually the most expensive, but comes with everything you need.  If its a CPU, it comes with a heatsink/fan.  If its a video card, it come with adaptors, software, etc.  If its a motherboard, it comes with cables, backplate, etc.  If its a harddrive, it comes with cables, software, etc.  It also means it comes in a normal retail box, and should have the longest warranty.  
 
OEM: Bare product only.  If you buy an OEM motherboard, chances are it will only have the motherboard.  (some include backplates.)  If its the CPU, you get only the CPU.  Should come in a retail box, just won't have the retail goodies.  The warranty is typically shorter, but thats because its supposed to be serviced by the OEM.  
 
Open box:  OB can be hit or miss.  OB happens because someone bought it, and then returned it for an UNKNOWN reason.  It might be as simple as he bought a S775 motherboard for his old S478 CPU.  Or he might have bought it, only to discover that the onboard NIC doesn't work.  Or it might be so bad that the entire MB doesn't work.  Either way, he would return it to the retailer, who then tries to sell it again as an Open Box item.  You typically get the item in a plain white box, with ZERO goodies.  Depending on who you buy from, there is usually only the manufacturers warranty, and a small return window.  (perhaps as small as 14days.)
 
Retail or OEM, no big difference for me.  For example, there is almost no reason to buy a retail hdd.  If you buy a retail motherboard, you have the SATA/IDE cable.  If you buy a newer PSU, it should have the SATA power plug.  The "retail" software can be downloaded from the manufacturers website, so you don't get anything there.  The only real benefit you get is the longer warranty.  You probably want to avoid open boxes, you might as well buy from someone on ebay who has 0-10 feedback points.  The risks might be the same.
 

 
WTF are you talking about?  The warranty is shorter because the OEM is supposed to take care of the drive, not the manufacturer.  I have never seen a study that shows what you are claiming, and I'd be surprised to hear that it is true seeing as both are made at the same time.

for saftey concerns, retail is ur best bet. u get the warranty, high chance it'll work fine, and if it breaks, again, u got the warranty. open boxes are there for a reason. its not worth the price paid, its not wat someone was looking for, someone u can relate to probably, or its defected/broken. OEM im not sure about my self, but to wrap it up retail ftw