Hi John -
I've been away from the group for a while due to a move from NC to VA. Still getting unpacked and pretty much no radio gear set up (yet).
You've received about all the recommendations and advice possible for getting started in AM. Don't be too discouraged about starting with a peanut whistle rig (100w or less) - that's what I was using before packing up to move. You can operate just fine, you just need to be a little more cognizant of time of day and band you want to operate. 100 watts on 40m is a powerhouse most days, until the band goes out. In the AM Ghetto area of 75m during evening/nighttime hours you'll be lucky to be heard, much less acknowledged. Band noise alone can be a challenge there, before adding in the stations on AM or SSB.
Heathkit made some excellent gear like the DX-100 some have mentioned. The Apache TX-1 is more or less an updated version but lacks 160m. Great iron, but the one thing you need to remember with Heathkit and a lot of early Johnson gear: since most were kits, quality varies by the builder. At best you'll need to do some basic maintenance unless you buy a recently rebuilt rig.
And of course, there are a lot of good tips and articles floating around on how to "improve" audio, PTT keying, and other areas if you're so inclined.
There's a great Tech section at www.AMfone.net
where you can read for days about the different rigs. Also a special section just for transmitter articles. And of course, a lot of talented folks there should you have questions. There are some especially good articles on the DX-60.
Have fun with it!