Replication nightmare

My company has around 75 W2K servers all of
them are Domain Controllers. 4 of them are at the headquarters and the rest dispersed nation-wide. Trying to have replication working correctly it’s a full time job. Our C: partitions are 4 GB and arerunning out of space everyday. Stagging areas grow up to 500 MB and replication stops when one server can’t talk to another. We have 3 Admins dedicated to monitor all servers, even though we make it work I believe it is such a nightmare. My question is this the way is suppose to be or are we doing something wrong? Anyone has a similar experiece?
All have SP2 installed. 2 DNS servers and 1 WINS server for the entire Enterprise.
1 GB memory and 2 CPUS 900 MHZ. per server