First of all, huge thanks to Ultraling and Maverck for having done most of the work and making this campaign possible. Both of them were awesome about letting me use their stuff to put this thing together. These are originally Ultraling's maps, found here in sc2mapster. I picked them up a long time ago and slowly worked on them, editing terrain, adding all kinds of flavor here and there, including Maverck's Brood War mod, and this is the result.
Features

all 10 original missions the tutorial
original SC1 units and structures with original stats, including custom models
original SC1 Terran soundtrack
all the dialogue, voice acting & other miscellaneous text from the original campaign
custom classic decals, such as Alpha Squadron, Sons of Korhal etc.

"Artistic License"

(some notable differences from the original campaign)

Medics! There were no medics in the original campaign, but where's the fun in that? Your marines need 'em
Kerrigan has the snipe ability (along with the original ghost abilities) because it's just too cool
Mission 4 "The Jacobs Installation" - you'll see
Difficulty level should be harder and actually keep you busy towards the end. Don't worry, I've tested it and I'm not that great. The final maps should give you a decent challenge though.

Download & How to play

Downloads: Map package - Mod file
put the mod file (SC1mod.SC2Mod) to your "Mods" folder in your Starcraft 2 install directory (NOT the folder under "My Documents")
extract the map package to the "Maps" folder in your Starcraft 2 install directory (create the folder if it doesn't exist)
make sure Starcraft 2 isn't running, and that your Galaxy Editor map test difficulty is set to normal (it is unless you've changed it)
drag a map to your Starcraft 2.exe or a shortcut and have fun!