If you download Adobe, you need to set the default program to open pdf's to Adobe.
Internet Options -> Programs -> Internet Programs -> [Set Programs] -> Associate a file type or protocol with a program
Then scroll down to pdf (it will have the Windows default utility selected), click on it, then change it to Adobe. Bing, bam, boom, done. I had problems with this and was having to download pdfs and do Open with... I did a little troubleshooting, and fixed the problem.