Here's my two cents worth!
The original poster claimed he's using the MTU Portable PC. If memory serves me, that is a "SHUTTLE" PC, correct? The Shuttle uses an NVIDIA Chipset. With the NVIDIA chipset you have a 5.1 sound system. The chipset drivers don't come with a small little program to re-assign your channels, but effectively, you can have 2 or 3 separate sound cards run off the front, center and rear output (the program takes away the In and Mic feature which I believe these other two stereo channels are originally assigned as).
Once you have the computer's NVIDIA sound card assigned as FRONT, REAR CENTER, then you can use the ASIO compliance feature (not supported yet in hoster I might add) to assign any of the non-default sound devices to other programs that use ASIO. One program that i use is called Virtual DJ. I found PC DJ limiting, as it only played MP3s. If you are like me and you use sound bites and other little funny things, you will note that you have some WAV, some WMA, some OGG, some whatever audio files INCLUDING MP3s. Of all the programs out there, I liked virtual DJ the Best. (If you plan on getting it, PM me, there are some quirks in the recent revisions to be resolved in the next revision, but there are work arounds)
Virtual DJ, similar to the program mentioned before (e-Jay) has dual trays, it will play sound FX (little jingles and what not) and it has dual faders for each channel or a crossfade feature that will fade the two. In addition, it has advanced mapping so you can assign Tray one to the left channel of your rear speaker out and tray 2 to your right channel of rear speaker out. Then you can assign your headphones to the center channel for cueing.
BE FORE WARNED, if you want hoster to work on its own channel, in your windows properties, whatever channel you have assigned as DEFAULT will be the channel that hoster will play with. If I may think out loud, hoster should have an internal ability to control its own audio but at a minimum select what sound device to play with. I know that that's a whole different codeing, but like I said, just thinking outloud ;)
So now you have these two programs running on your computer, but let's say that you don't have but two channels? Most mixers these days have a "CUE" feature on it and you can plug your headphones in to it. Once you do that, you can let the audience hear what is turned up, and you can cue up your jingles, bites, or whatever.
I run my show with the following running in the background: Virtual DJ, Hoster (current version), Microsoft Excel (for song searching), whichever recording software I'm using and anothe program that I am testing as a VJ software. BTW: Thanks for the CORE, I'm interested in checking it out as I converted a lot of my video bits from DVD, LD and whatnought to DIVX and like to play them on the big screen, maybe that will be what I can use that is better than Windows Media player and the last 10 programs I've tried.
One last thought, whether you are using a laptop or a pc, you can always go out and get a USB sound card. Creative labs has one that is based on the SOUND BLASTER live and it cost less than $40.... If you plan on recording from a laptop, this is a must as MOST laptop manufacturers do NOT include a line in feature, just a mic in and as we all know, that sound terrible when recorded.
I just bought myself, for my show, a Mackie Onyx Board, it comes with an optional FIREWIRE port to record every channel in and send back 2 channels. There is another piece of equipment out there that DJ / KJs should look into, it is the RANE MP4. This little device controls 6 line (or phone) ins and two of them are two separate USB AUDIO devices that will show up in your PC. It is a cross fader and takes up 1U (That's one rack space). It is a bit pricey at current prices (not seen one onthe street yet), it is $500.
Hope this info was helpful to you. If you have any other questions, you can send me an email from my website,
www.barkaraoke.com or leave me a message here.