Hello intelchiq and welcome to mobileread.
Sorry to hear that you purchased books that will not work on your new reader. Hopefully the B&N drm will be supported by all devices supporting epub sometime in the future.
In the meantime, you can visit any other ebook store that sells epub to buy your ebooks. There are a lot of them around. You can use websites like
http://ebooks.addall.com/,
http://ebookprice.info/ and
http://inkmesh.com/ to look for a specific title or author, and find a list of ebook stores that sell them.
Fictionwise, Books on Board, Kobobooks are some good ebooks stores selling epub that you might want to check out.
Have fun with your new sony!