Geez, this is a hard one, just based on the information you provided, so I'm just gonna give my two-cents worth and let others add.
Based on what you've described, here's what I'd like to know:
1) How many PC's are you connecting at the church?
2) What are your file sharing/printing needs?
3) Is network security a concern?
3) What are all 5 hotswap drive bays loaded *with*? That should prove interesting.
In short, WIN98 doesn't act as a stand-alone server. Depending on you networking needs, and the number of PC's involved, a peer-to-peer network solution sounds like it's your best bet. In any case, your end users won't notice a difference if you run an NT Server with WIN98 clients. Also, the Compaq 1500 is a retired product with not much processing speed or memory. But that's no problem and won't affect your network if it's not too large.
I'm sure others will have more input about your question. In any case, I'd use what you have as a learning opportunity (as long as you don't disrupt the services your users already enjoy!).
Peace, and best of luck,
Mark Mcade