NesterDC is far from obsolete... it's still the best NES emulator availible on the Dreamcast, and Scherzo (the maker of the emulator) is making a new version of the emu called NesterDC SE (for Special Edition). It will have screenshots and title screen shots for every game, a FAQ guide from GameFAQs for every game, and tons of other wonderful features packed right into the SBI file. He's even taking suggestions from people on what should be included in the emu on the dcemulation.com message boards.
But to answer your main question... I have no clue where all the NesterDC themes are located these days. NesterDC SE has a nice looking theme built into it though (I think you can even customize the colors). You might just want to wait for it to come out.
Bookmarks