DZ Motor...
Here's a bit of a step-by-step... this happens often and can be resolved in less than a minute.
1. Open your System Properties
Right-Click on MY COMPUTER and choose Properties
or
START > SETTINGS (not always necessary) > CONTROL PANEL > System
2. Click the ADVANCED TAB
3. In the "Startup and Recovery" area, click SETTINGS
4. In the "System startup" area you can note that the Default Operating System dropdown box lists 2 options. You will be removing one of these. Click EDIT
5. boot.ini will have opened in Notepad. Assuming that your new operating system is the one that starts by default if you let the timer count all the way down, you can DELETE the bottom line (old operating system entry) from the boot.ini file.
It should start with something that looks similar to:
multi(0)disk(0)rdisk(0)partition(1)
6. Close the Notepad window and answer YES when asked to save the changes.
You're done. Let me know if you need further help. :)