First time reformatting. No info on this PC. Need a little assistance

My wife just scored this computer at work for a killer deal, put it this way, the monitor is worth more than what I paid. (Crack heads?) Anyway. I've never reformatted a PC before but I've done a little reading and it seem's like something I can handle, but I've come across a huge issue. It's running Windows 7 Ultimate in an HP Elite e9120y case with a modified MB and 4GB less memory than OEM. Also it came with Vista not Windows 7 so I have a feeling it's not genuine. So I'm worried if I reformat and install Windows 7 Ultimate with this Key I'm going to have issues with activation. It does have the Vista Ultimate OEM Sticker on the case though. Though from what I hear Vista is garbage. This thing really needs a reformat but I don't want Vista on it and really can't afford a new copy or upgrade to Win 7 atm. So step one, can I test this current key if its Genuine Windows 7 Ultimate? It does say it's activated but my computer friends say that doesn't generally mean its a 100% legit key, which I don't understand. Problem #2, with the modified MB the OEM key would no longer work, correct? I think I bought a nice paper weight and ultimately got a decent deal on a monitor, until I can atleast afford a full copy of Win7.

 

Not really sure what you mean by "modified" MB. As for the key, no idea what sort of key is being used for W7 on your machine. Download mgadiag.exe (Google it), run it, post the screenshot of the Windows tab

 

Sorry, not too great at explaining things. It's not the original motherboard, it's a BIOSTAR TA785G3. It's actually Windows 7 PREMIUM not Ultimate, but this mgadiag shows part of my product key, is that ok?

 

No idea still what you mean by "not original" and how does it matter here. And yeah, it is OK that it shows part of your product key.

 

May be the OP means that the original MB shipped with the system has been changed in some way or it's entirety, hence the driver disks supplied with the PC will no longer be valid.
In any case, your wife needs to enquire if the PC was activated with a corporate license of Windows 7, which I highly doubt since Windows 7 Home Premium does not count for corporate licensing.
As far as Vista being garbage goes, it's not true, at-least at this point in Vista's lifetime.
Download a copy of Vista, find the correct drivers as per the mother board, and format the system.
In my experience, if configured properly, Vista runs about as smooth as Windows 7 on average hardware. On low end systems, sure Windows 7 runs better.

 

back up your windows partition first with a free image software (macrium reflect), also backup all your drivers with the free drivermax. Now you can do the reformat.
My recommendation is to get easus partition master (free) or gparted (free) to format your drive (both of these boot up pc from a bootcd). This way you can get a good look at the drive and see if there are any hidden partitions etc. You can also split (partition) your drive example use 50gb for your your OS and and the rest for data partition.

If your new windows installation doesn't work, you can always reinstall the original windows from the backup you made. If the original is slow, there are ways to make it faster without reinstalling windows.