Mal,
They are held in a different city each time (every second Easter).
The history of the event can be found at
http://www.fefcholden.org.au/nats but in summary:
1988 #1 Ballarat, Vic
1989 #2 Wagga Wagga, NSW
1991 #3 Adelaide, SA
1993 #4 Bendigo, Vic
1995 #5 Sutton (Canberra), NSW
1997 #6 Mildura, Vic
1999 #7 Adelaide, SA
2001 #8 Sydney, NSW
2003 #9 Gold Coast, Qld
This is the first time it has been held in Queensland. The 2005 event will be hosted by the FE-HR Holden Owners Club of ACT, probably in NSW somewhere not far from Canberra. The venue has not yet disclosed.
And anyway, the idea is to drive the cars. That's what the majority of entrants do. Getting there and getting home is half the fun when you're in a convoy with your club mates
You didn't say what part of he country you're from. If you're in Darwin or Broome then everywhere's a long way - at least until the FE-FC Holden Car Club of WA gets formed!
Hope that helps,
RET