paulec, I would recommend you to listen to EricTRA. An installation of GNU Linux Ubuntu as an Wubi does not mean you have a dual boot system. This is my suggestion:
Step 1. Save all personal data you have like documents, bookmarks and such. Preferable to an extern HDD.
Step 2. Remove Wubi from your system and make sure that you have burned out recovery disc from your system. Contact your computers manufacture if you are unsure.
Step 3. Download and burn yourself a fresh copy of GNU Linux Ubuntu 10.10. (Or Linux Mint 10 Julia which is based on GNU Linux Ubuntu. Linux Mint is my favorite
Step 4. Insert your copy in the optical drive (the CD/DVD unit) and restart. Depending on your machine, you can temporarily choose to change boot order, often called "Boot menu" at start. If not, you will have to go into BIOS and change boot order to CD/DVD. The computer will now reboot or enter boot menu. Make sure that you choose CD/DVD.
Step 5. Boot up Ubuntu or Mint. Log on in as an Live Session. That enables you to better connection to Internet.
Step 6. Choose "Installation". The guide that follows is pretty much self-exploratory. The only thing is that you choose to divide the HDD into to parts, one for Windows and one for Linux. The installation should take about 20 minutes.
Step 7. Done! Now you have a fully dual boot system with an Linux part and an Windows part.