The conversion to 4e went pretty well. Needless to say, there's a substantial learning curve, but by the end of the second combat scene, the players were all getting the hang of it. I made a few mistakes along the way, namely setting both of the combat encounters in hallways that were really too narrow to allow for much in the way of tactical/movement options, especially with seven PCs. On the other hand, in terms of balance, I think I got the encounters right. The first one (a horde of zombies) felt suitably tense, with a couple of PCs hitting bloodied status along the way, but no one really being in danger of dying. The second (featuring ghouls, with some minion undead support) would have been much better if it hadn't ended up taking place in a choke point.
And speaking of that second encounter, here's the Initiative lineup:
No fewer than four of my seven players rolled natural 20s on Initiative for that fight, and only one rolled below a 15. I don't think I've ever seen one stack up like this.
We were only able to play for about three hours due to social obligations, but that allowed us plenty of time to hit the favored pizza place to wait out the end of the world. And since that didn't happen, I guess we'll play again in a few weeks. I'm a lot more optimistic about the remaining rooms on this level, as I decided to completely abandon the existing floor plan of the dungeon I was using and build my own. Getting the creative juices flowing, even if it's just laying out dungeon tiles and giving names and motivations to stat blocks is a far sight better in my book than simply running someone else's adventure.