I need to upgrade my computer...any suggestions?

And you will need a big power supply, but if its a prebuilt machine the manufacturer will put a PSU that will power everything, but shoot for 1000w or more, don't settle for less

Well personally I prefer to do custom PC's as they are just cheaper in the long run. But as your corporation would buy it for you then a prebuilt workstation is probably the best bet. For video editing I would recommend an SSD for an internal hard drive, allows premiere to read and write files a lot faster. For a processor an I7 or Xeon both work great for editing, I7's have been out performing Xeon's recently,  but if this machine is solely for editing I would go with a Xeon processor,  but if you plan to do other just work things then I would go with an I7. Minimum of 16gb of ram, more never hurts but anything less and performance might suffer. For the GPU go with an NVIDIA card, a 1080 would do you more than well but they are also pretty pricey. I would say though for whatever GPU you get make sure it has at least 4gb dedicated memory.

Are you looking to upgrades certain parts of your computer or just a whole new system? If you are looking for just specific parts I would say your GPU first, as you can tell premiere to use your GPU for rendering purposes