Unrecognized Device

Ok!  So I'm trying to migrate over to Win 8 64-bit from XP 32 bit.  I was able to do a clean install from the upgrade discs (Woo Hoooo!)
 
The only thing that HAD to change in my system was my graphics card.  My older card was not Win 8 compatible.  I installed a new Gigabyte Radeon HD 5450 PCI express card.  No issues during the install.
 
So . . . . . the issue at hand is that I have an unrecognized device that is causing me problems.  All I know is that it is a PCI express device.  Naturally, I disconnected my external devices one at a time to see if the issue went away.  Nothig changed during this process.  I was susp***icious of the new graphics card seeing it has an HDMI port.  Thinking this might be the issue I removed the new card swapped it for the old and no dice.  The "Unrecognized Device" is still showing up in device manager. 
 
The obvious issue I am having is that I have Garritan Authorized Steinway.  When I go to load the samples they load very, very very slowly then I get an error message and the system needs to reboot.  The same happens even if I disable the Unknown device from device manager.  I'm at work and I appologize I can't remember the message.  I should have been more prepared to post this.
 
Anyway . . . . . .   any ideas how to trouble shoot this problem.  I have not tried removing any of the additional cards plugged into the motherboard (USB, Firewire . . . . . )  So I haven't really ruled out ALL of my equipment.  Prior to migrating over to Win8 I did do the system check from the Microsoft website and my graphics card was the only incompatible device I had in my system.
 
I realze I have an older system.  A new machine would be great but not practicle at the moment.  This system has worked flawlessly without issues until now.  Any suggestions are greatly appreciated.
 
Regards,
Rich

Jim,
I'm humbled by you chiming in here.  Thanks!
 
I am trying to be patient here.  I do realize that I am treding new teritory with Win8.  I figured skipping Win7 was the better path for me.  I may end up reconsidering .  This is all new to me.  I know enough(which isn't much) to be Dangerous !
 
Bullet item 1:    I disabled the unknown device and this didn't do anything to clear it from showing up in device manager.  I did also swap out the video cards.  However, I will go back and check the audio devices and disable the suggested device.
 
Bullet Item 2:  The answer is no!  All I did was the installation from the Windows media disc.  I do have the original drivers that came with my machine however I am not certain if they would be Win8 compatable.  Is there a way to tell if the drivers I have are?  I imagine these drivers/managers would be available from the manufacturers website.  I have an ABIT motherboard.
 
Bullet Item 3:  I guess some of what I mentioned in #2 would apply.  Would I need to adjust or "turn on"any of these parameters, assuming my motherboard has this ability?  This is out of my scope of knowledge. 
 
Thanks again,
Rich

Jim,
Thanks for your suggestion and I certainly respect your opinion.
 
You did NOT say that this setup wouldn't work under Win8,, however I would like to salvage my investment thus far.  Switching gears at this point wouldn't go over well in my household at the moment   .
 
So, is this do-able? And, in your opinion, would I get good results?

Thx