DOC,
I take it you're flying the default 737-400 that comes with FS2004?
If you are, you really need to look at the PMDG 737NG series of add on aircraft. You can find them here :
PMDG Website
This package includes the B737-600/700/800/900 and has options for winglets or not.
The only way I can describe this package is that it is the closest to the real thing as I have seen.
Fully functional MCP(VS mode/N1 mode/LVL Change/LNAV and VNAV/Bank angle limiter/Speed and ALT intervention buttons/CWS mode and full autoland).
FMC is about 90% of fully functional(Full LNAV and VNAV functionality with speed and path descents. Calculates V1, Vr and V2 depending on your GW and T/O flap settings with callouts, fuel flow computer so it will calculate VRef for a flaps 15, 30 or 40 approach. N1 limit page for derated take offs and climbs. The list goes on...)
TCAS is also available with full TA/RA functionality with the MCP/FMC and it also has GPWS!
Flies like the real thing(as reported by 737NG pilots who beta tested the product) including spoilers that aren't very effective.
This will completely immerse you in 737 procedures and I think you'll find it just as much of a challenge learning to use this plane as you did learning the approach procedures.
Sort of looks real nice aswell!
In fact if you have a look around, you will find a lot of add ons for FS. Some are freeware and some are not. I generally find that the payware add ons are less troublesome and are, 9 times out of 10, worth every penny.
Anyway, hope this helps. Any other questions, just drop, me a note.
Cheers!
Paul.