Each application basically has it's own filesystem with all it needs to run installed therein. That would certainly have confused me mightily.

Are the virtual drives (if I've used that right) dynamically resized files that vary in size with  with demand? Must be something quite clever happening there.

A couple of questions, if I may.

I rercently established that my slightly less ancient desktop (a Dell GX 620 with 2.8 gHz P4/hyperthreading) is theoretically 64-bit capable - must one of the earlier efforts.

BIOS describes the CPU as Intel EM64T; googling suggests this was early (64-bit) days indeed.

The Mint 13 64-bit live CD runs beautifully, and I'm tempted to upgrade the current Mint 9 (32-bit) to Mint 13 (64-bit.)

Obviously, I'll back things up first - way overdue, anyway.

Is there any reason not to retain the current /home partition, as I would do were I simply upgrading to Mint 13 32-bit? In other words, tell the installer to go ahead and format the current / partition, but to ignore /home.

I've no idea whether this might lead to difficulties getting the new 64-bit system partition to talk to data organised under 32-bit. (I could just try it - if it doesn't work, then wipe the current /home, replace and then copy the backed up data back - bit tedious, though.)

The current set up is as per the attached screenshots. /dev/sda runs Windows XP (or does when I get round to using it - bit of a waste of space at the moment); I also use a couple of NTFS partitions on it for storing shared data (as in shared with Mint - not used, so far), and distro isos (not a good idea, it turns out - F 32 would have been better; I suspect ext3 would be better yet - VBox moans about booting off isos stored on NTFS or ext4 - changing that can be a project for later).

/dev/sdb is essentially Mint 9's partition, with /, /home and swap, plus an arbitrary partition for trying out new distros.

Another question mark concerns the live (64-bit) DVD's use of RAM. It only seemed to see 3.4 GB, although there are 4 GB of RAM installed - just like the 32-bit system. I can see no options in BIOS for enabling PAE or anything esoteric like that. In fact, BIOS offers very little customisation (and no virtualisation, bah.) The 64-bit live DVD runs pretty fast; odd that it only uses 3.4 GB of RAM - have I misunderstood something, or is there something I should change?

My usual waffling - sorry. In essence - any reason I can't just upgrade my current 32-bit Mint 9 / root partition to 64-bit Mint 13, without changing anything else?

And does the live DVD's insistence on only seeing 3.4GB of RAM imply any problems ahead?

Off out shortly, and it'll be a few days ere I try this - but I'll keep looking in from time to time for brilliant suggestions - TIA!