Upgraded from Windows Vista Home Premium and having problems

Ok, so today I bought the upgrade for Windows 7 and I ran it on my Notebook and everything went fine until I had to put it on a disk. Now I got my computer used and the guy had partitioned the hard drive and their wasn't enough space on the C drive so I put Windows 7 Ultimate on my D drive. I was stupid enough to think that it would just over right Vista but I guess because I had to put it on a different partition it didn't. So now I have to dual boot, and I figured I would just move all of my important documents and files from Vista onto Windows 7 using an external hard drive, but I was wondering if I could take Vista off my computer some how and un-partition my hard drive myself or if it would be a big deal and I would have to have someone who knew what they were doing do it. I don't know much about computers but I'm not completely computer illiterate. I would appreciate any help that I could get. This is my first time on a forum like this so I'm sorry if there is a post somewhere like this. Thank you.

Keyhero,
Welcome to Seven Forums.

I recommend following the procedure given in the tutorial I list:
Clean Install with a Upgrade Windows 7 Version

Back up your files to external HD.

Follow the steps here to wipe the HD clean first so you will have the cleanest possible install: SSD / HDD : Optimize for Windows Reinstallation

Now reboot with the Win7 DVD in tray and it should autostart, install to the partition you made.

The Win7 installer is mostly driver-complete, with newer drivers arriving quickly via optional Windows Updates. You'll need to get online to get them, however, so be sure your wireless driver is backed up to external so you can install it if the installer doesn't. Find your wireless driver on the manufacturer's Support Downloads webpage for your computer model. If you use a wire, back up the ethernet driver.

After updating drivers from optional Windows Updates, look in Device manager again to see if any drivers are missing or in error with an (!) exclamation mark. If so, download and install those drivers from the computer's Support Downloads webpage.

Install programs slowly over time to gauge any performance changes. Don't let any programs write themselves into the msconfig>Startup list besides AV and gadgets as they freeload on CPU/RAM and can spy on you. Use a lightweight free AV like MS Security Essentials or Avast 5.

When it is finished, clean and order your HD perfectly using state-of-the-art CCleaner and Auslogics Disk and Registry defraggers. Then save a Win7 backup image externally so you never have to reinstall again.

Locate Device Manager, msconfig, Windows Update by typing in Start Search box.