I use SetiHide on several machines. It lets you do the following:
Cache WUs. You can decide how many to cache.
You can use a network cache common to all SetiHide machines on a network so you only have to manage one cache, and not really worry about the cache on individual machines.
Run in either online or offline mode. On online mode in transfers the completed WU and gets a new one automatically.
Schedule a flush and fetch of WUs so that it happens whenever you want it to. This is used in conjunction with offline mode.
Specify a SetiQueue to run through.
Start either invisible or in the system try or in a window. Invisible is what you are looking for.
Transfer WUs with a floppy to machines not on the network.
It also keeps a log of WUs. I am not sure how much info is in the log, I have never really looked at it.
It will also start while a machine is sitting at a login window on a Win98 machine I have at home. I am not sure if it keeps running when the user logs out or if it will stop and then restart. I will have to check on that.......
Hope that helps some...... It has run pretty stable for me.