I just bought the new version of Nero.

A burned a collection of Mp3s as an iso file onto my harddrive.

I then mounted them via Dameon Tools.

Whe I then went to Simple Burn, it wouldn't recognize the mounted file as a music disc.

Is this something, some "upgrade" (screw-over) for Nero 6?

Of course, the whole point of all of this is so I can use Simple Burn to burn my MP3s to disc without having to use Sony's other bloated software.

Question #2: if this mount trick is no longer possible with Nero 6, is it possible for me to run two versions of Nero on my computer at the same time? The old version of Nero Burning Rom so I can still do this, and the Nero 6 Suite that I just bought?

Sorry, I'm new to this forum. I changed my question and, unlike some other forums I'm part of, here, you can't change the title of the post?

You minidisc experts out there...any help with the new question would be appreciated.

First of all, Nero 6 can still burn images to disc, the problem is that it's a little tricky. You won't need Nero 5 anymore. In order to burn to your hard-drive with Nero 6 (to create an image *.nrg or *.iso) you only have to select in the drop down list in the toolbar where your recorder would be listed Nero Image Drive or sth similar. Once you've finnished your compilation hit the burn button -> this will show you the tipical burn menu where you can select speed/type of burning (DAO or TAO) -> hit "Burn" or "Ok" and will appear the Burning Window requesting you for a place where you can store the image file.
As for mounting your image you can use any software (Alcohol 52% or 120%, daemon tools...) but it won't be neccessary, you don't need to mount to a virtual drive and then burn. You can burn directly or if you prefer you can save your project as an image as indicated before and then record the image file either using Nero or Alcohol120%.
And finally about minidisc.. I dunno anything about them, but I only know that they need special discs (not 12cm/8cm cd-r), so.. what's the point of your question?

For the mounted image to be recognized as an audio-CD, it has to be an audio-cd image. when you used nero, did you make a "data" compilation, or an "audio" compilation?

You cannot make an audio CD image as an ISO, since the ISO format is limited to a single data track with 2048 byte blocks, so in Nero, it has to be NRG format (Nero's own).

For audio, I'd prefer to use a WAV/CUE pair - or even MP3/CUE.