Hello. I currently own this: http://support.hp.com/us-en/document/c00213821 and i am thinking about doing an overhaul but still trying to use the case and psu. I am looking at http://m.newegg.com/Product/index?itemnumber=13-130-755 to replace my mbb. My main question is if i stick with this case and i use the usb3.0 header can i connect that to my existing front usb ports? If so will they now be 3.0 or would i be better off scrapping the case? Thanks.No, USB3.0 headers use different connectors from USB2.0 headers.  Scrap both the case and PSU.  The PSU is old, not very good and will not have the rail weighting or connectors for a MODERN system.  Using it is only going to cause trouble.

You would be much better off selling the full machine as it is for whatever you can get, then put this money TOWARDS the new parts.  There is nothing in that system that could be reused unfortunately.Thanks again. I was kind of afraid of that. The original psu ACTUALLY went out about 3 years ago and was replaced with a more modern dynex brand psu. However seeing as that is still pretty old I will more than likely end up slowly piecing TOGETHER a rig. Been debating going full ATX anyway but now I have a reason to. Thanks again. I will open a new build thread when it comes time for me to make HARDWARE decisions.Dynex PSU?  Those are total junk - Do not even think about using that with a new PC.

The PSU is one of the most important parts of the PC, never cheap out on it.  You should only look at good brands such as Corsair, XFX, Seasonic.etc and shouldn't expect to pay less than $12 for every 10w that the unit is rated for (excluding any sale prices).