Did the nest have fur and moss in it? They sound like chickadee eggs. Could be house wrens too.

I wouldn't recommend buying decorative birdhouses for anything other than well, decorations. The wood is just too thin and they can't be opened to check on the eggs and nestlings.

If you want to provide a nesting place for birds you should get yourself a nice nestbox that has a hinged roof or side to make checkups/spring cleaning easy. You could also build one yourself. There are lots of free plans online.

here's some great ideas/suggestions for choosing a bird house

Here is a link that might be useful: Choosing the best bird house design

The Bluebird site here & Sialis site have tons of info about how to safely house birds. It requires some labor but the rewards are priceless. That said, I had Carolina wrens nest in a decorative house that I thought I had plugged the hole. Mama raised 4 young sucessfully after I moved the flying pig birdhouse to a safer spot than the porch rail.
Susan

My grandmother gave me two birdhouses. One had three holes, so I had to plug two of them. I am painting them with latex paint. That's safe right? It is waterbased and nontoxic.

If you are new to birding and interested in providing houses for birds please visit the bluebird nut cafe and ask any questions you have, we will help you with everything you need to know!

http://bluebirdnutcafe.yuku.com/

I know that others here will disagree, but I find that my Chickadees adore my decorative porch birdhouses and use them every year successfully. The key is choosing the right decorative birdhouse, and MOST of them are not serviceable for the birds. I look for a house that is sturdily built, has the right sized entrance hole, and has a big clean out in the back. I would not suggest hanging them in a tree because that just seems to invite trouble. All of mine are mounted up high on a porch post. As for bird housing in the yard, I would stick to strong regulation housing mounted and protected appropriately. I am posting some pics of one of my most successful decorative houses so that you can see an example of what I am saying works here for me.
Angie

And, here you can see the BIG clean out in the back.
Angie

I have a three post trellis on which my hardy kiwis climb. On each post I would like to mount a bird house. I am in N. VA. Any advice on the types of birdhouse, etc.

Well Charlie, you first have to consider which bird species might actually use a box in that location. I am thinking Chickadees or Wrens are most likely. So, a nice sturdy box that is intended for Wrens would be good. The entrance hole on Wren boxes would work for Chickadees or Wrens. You don't need perches on the box. Most species of cavity nesting birds will not nest too close to more of the same species. So, I would start with one or two Wren boxes. I would watch them closely and make sure that the House Sparrows don't take them. Some here would tell you not to mount any birdhouse on a trellis for fear of easy access by snakes. My feeling is that cavity nesting birds were successfully using tree cavities well before man began to offer custom built housing for them. So, I would say go for it. Just don't let the House Sparrows have the boxes.
Angie

See all about mounting nest boxes at the link below. Don't set your birds up for disaster! Protect them! :)

http://bluebirdnutcafe.yuku.com/topic/5934/How-I-install-a-nest-box

-Tyler