Dia's Muire dhuit.
Byki and the Transparent Language System works with Vista and Windows 7. I have both, and aside from having difficulty printing flash cards (Which may be just my printer, I don't know as it prints lessons and help topics just fine), everything else seems to work alright. I use Byki for vocabulary (It's a virtual flashcard program) and Transparent Irish for both vocab and grammar (Transparent Irish is a series of immersion environments). I've tried Rosetta Stone for Japanese, but I didn't like it, so I wouldn't use it for Irish. I can't remember if there were any translations in Rosetta Stone, but there's translations for everything in Byki and Transparent Irish.
http://www.byki.com/
http://www.transparent.com/learn-irish/
Byki and Transparent Irish are a whole lot cheaper than Rosetta Stone, and have worked very well for me. I found Rosetta pretty boring and couldn't get into it.
Also, you can read an old Irish grammar book here.
http://books.google.com/books?id=ezIWAAAAYAAJ&dq=subject:%22Irish+language%22&lr=&source=gbs_navlinks_s
It's the full book, and you can even download a PDF file of it if you want.