Can somebody tell me what files I have to copy on the SD MEM-card in order to put one or more Map(s) for use w/TT ONE XL unit? Or give me a link if there is one...
THANKS IN ADVANCE

You need a Navcore and a map on the SD card.
Check the red sticky threads and the tutorials first.
The 9.205 Navcore for 32mb devices should work for you, for the map check the coverage you need and select a map that suits your Navcore (check the chart in the map thread).
Hope that gives you a good start ;)

Thanks Downunder35m.

After my post and before your answer, I read some info on this fantastic site (I was pressed to "fix" my friend's TT - I had messed it up trying to put the map of Argentina - and load the Argentina map because he was ready to fly there. Actually I have put a navcore 8 (not 9 -hoping that it is "lighter" than 9) and the map of Argentina (my friend left for Argentina yesterday!!!) on the SD card. When I had no SD card inserted it ran from internal memory the W-Europe map (in the internal memory), When I insert the SD card (w/Argentina in it) it runs the Argentina...

But I think it is "strange" and "memory-hungry" to install the Navcore on the SD card, too. Why this? Does this also happens to "legal" installations?
A friend of mine (with a different TT model!) told me this morning that you do not need to load the navcore on the SD card - He actually told me that he has the map on the SD card and uses the internal memory to load mp3 files - perhaps he uses "legal" versions only.

Two more questions:
1) Navcores 8 and 9-what are their differences?
2) The max size of the SD card depends on the NAvcore or on something else?
(I am a GARMIN guy and it was the 1st time I had a TT unit to "play" with.

Thanks in advance

It all depend on the actual Navcore, the map you use and the amount of poi's showing on the map.
Often the easiest way to speed a device up is by disabling all poi's from showing on the map, and only activate the one you really need.

1. Navcore 9 can offer a 3 pane status bar and supports the maps with housenumber info in it, other than that there is no real difference
2. Only the bootloader, but you need at least Navcore 8.2xx for effective use of SDHC cards.