This would be my suggestion as well.I then ran Reavers of Harkenwold from the Dungeon Master's Kit followed by Cairn of the Winter King from the Monster Vault. Gardmore Abbey is next.
This would be my suggestion as well.
Although I'm sure you can find enough 1-5 level adventures in Dungeon. Low level adventures are the most common I think. Also I hear Slaying Stone is pretty good. However, don'tuse Orcs of Stonefang Pass; I hear that Gardmore Abby has lots of orcs in it.
FWIW I've gone The Twisting Halls (from the red box) - Slaying Stone - Reavers of Harkenwold parts one and two - Orcs of Stonefang Pass (and may not be able to squeeze in Cairn of the Winter King before cracking on with Gardmore). I've made a variety of changes as I've gone, linking Slaying Stone to Reavers (in order to help Kiris Alkirk (spoiler for Slaying Stone and Reavers)In response to the spoiler comment:I haven't read Orcs of Stonefang Pass yet, but I presume it's orc-heavy. Gardmore Abbey has one section with orcs. So, they exist, but it's not wall-to-wall orcs - although the orcs in the adventure do come at what will be the beginning for most parties.
Speaking of Threats to the Nentir Vale, there are lots of adventure hooks in there if you want to craft your own adventures.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.