Did you know that you can import OPML files into Google Reader to subscribe to feeds.
Simply go to Manage Subscriptions...
...then click on Import/Export, browse to the OPML file you want to import and then click upload. (You can also export your Google subscriptions if you would want to import them into another reader, of have a backup copy in case you mess something up.)
Recommendation: It is a good idea to have your feeds assigned to folders, making them easier to manage. It is also possibly to manipulate the OPML to put items in folders you already have setup, but I'll probably let someone more in the know on that one give insight on how to do that.