Try:
http://www.altair32.com/
Rich has an excellent Altair emulator and also has plans for a real front panel to interface with it. I use his emulator with a real ASR-33 Teletype. It works great!
Also try:
http://www.brielcomputers.com/wordpress/?cat=11
There might be just what you're looking for (modern PC in an Altair case.)
Let's keep this board alive for more than spammers!