You can do this by right clicking on My Computer and selecting Properties.
Click on the Computer Name tab then the Change button.
Make the name something unique.
Note: Don't confuse Computer description with Computer name, they are not related.
As for the unknown devices in Device Manager:
Right click on each in turn and select Properties.
Click on the Details tab.
There will be a line like this:
Post that much from each. You can then (or we can) search Google and that will almost always tell you what kind of device it is.