I think the missing piece of info here may be that you have to actually start recording to monitor through Reaper. ie just hitting monitor on an armed but not actually tracking/recording track you will get no effects. at least thats how mine is setup/default?

I think I am recording correctly, because my tracks are coming out nice and my mixes quite good. I am just trying to understand the flow of sound from voice through mic to mixer, guitar through effects box to mixer, out from mixer to interface to puter, from puter back through interface to mixer and how you listen to the recorded tracks, then record the next track, with or without input monitoring selected on the track being recorded. The last phrase is the snag, you have to choose a monitoring method, OK, psingman

You need to get the mixer channel you're sending to Reaper into the 'phones too. Turn on 'Tape to Control Room' and 'Mix to Control Room'. Sounds like you're using a Beringer mixer?

Send me your drivers and I will see what I can do. I have an Edirol FA101 10 in 10 out that I have used to play some shows ( guitar backing) live without using an amp, just reaper or nuendo 2 running Guitar Rig 2 and Amplitube 1.2 ( still my all time favourite) the Latency I get with the stock drivers is 5ms at best With the modified drivers and reg hacks I get 1.2 ms which is pretty close to fx units. This Edirol is hooked up to a desktop pc running windows xp sp2 with Nuendo 2 and Reaper 4 on the Edirol firewire interface. I will look up your drivers and see what I can do