We can't tell you much if we don't know what you're working with.
What operating system are you running and is it up to date?
Do you have any diagnostic or maint. programs installed like CCleaner?
If you're running a version of MS Windows, do you know how to run the Win Uninstall command?
Which version of DW are you trying to get rid of? If you have the install CD, what does it say on it? Where was DW installed to? What was the file path?