Using Multiple Devices With the Play Store I've been using a Droid (original model) for a while and recently I bought an Archos 7 Home Tablet at Office Depot (I think it was on clearance, but I don't remember why it was marked down).  I registered the Archos tablet online, then tried to download some apps so I could start using it.

The selection was small, so I went to the Play Store and logged in with my Google ID.  When I tried to download apps, it told me they would not work on my phone -- but I was using a tablet.

This tablet is not the easiest to type on (which shouldn't be a big issue for what I have planned for it), and that's making it frustrating trying to enter data for forms or to deal with anything.  At this point, my understanding is that Archos seems to have their own app store that I was using when I registered my tablet.

But now I want to use the Play Store I linked to above, but when I go there, it always tries to download to my phone, not to my tablet.

How do I tell the Play Store that I have multiple devices and tell it to download apps for the device I'm using?  I tried setting up another Google account, but it wants my email address and when I give it, then Google says it's used by another account.

How can I use the Play Store with both devices?
The first thing you need to do is to check your tablet version. My suspicion is that it isn't running Honeycomb (Android 3.0+ or the tablet version of Android) but actually a heavily modded phone version of Android (i.e Android 2.1-2.3).

Go to settings -> about phone (or something similar. each manufacturer changes how you access this)

If it is indeed running the version of Android meant for phones, then the market might be complaining to your tablet because you might be trying to download apps meant for honeycomb. 

The online market automatically updates to include additional devices when you activate them (i.e when you initially do the android setup and sign in to your google account). Make sure you select the drop down and check if there is another option. Also make sure you activated both devices under the same account.

-I know I should have made this a comment but its too long of an answer for one. :P