There are specific headtubes for each particular headset. Also, if you plan to install your headset yourself you will need a headset press (you can buy one or make one). If you are not that great with tools Id just buy a headset from your LBS and have them install it. Headset Press:
Looks to be a standard threadless headtube. Measure both sides of the tube, most likely it will be around 1 1/8", it could be a 1" though. As mentioned you will needs some tools to install it, if you are a tool guy (buys/collects tools) go for it. If not go to a shop and have them do it (educate yourself on headsets before you go).
Look at post #25. I find this the best way to remove a headset. Cheap, simple and works great. 1 1/4 inch washers are usually a touch oversize and most measure right at 33 mm just like in the picture. I have used this with a short 3/4 inch PVC pipe for hammering out the old headset or a wooden dowel works too.
This is a slight variation on the homemade installation tool. The different idea is the use of copper plumbing reducers. Usually you don't need these, but if you run into one that just doesn't want to go in straight without cocking, these tend to self center and work better than if you don't have them. Also easier to keep in place than simply flat washers which comes in handy when you don't have three hands. I think the article has an error on sizing. He says it is a 2 inch to 7/8ths reducer which is close OD, it will be listed at the hardware store as 1.5 to 3/4's reducer.
At the very least the flattened washer is a great idea for headset removal.