.... aaaand over we go to Downloads !      

Nice going.

What's that icon between Chromium and Caja ?   
I typically install MATE (on other distros) using Synaptic, and selecting  mate-desktop  alone picks up the dependencies.  Do you need the multiple commands to get the extras ?

As an indicator, the following quoted from Mint 18 (based on U 16.04) release notes :

    The 64-bit ISO can boot with BIOS or UEFI.
    The 32-bit ISO can only boot with BIOS.
    The 64-bit ISO is recommend for all modern computers (Almost all computers sold in the last 10 years are equipped with 64-bit processors).

ONLY an indicator - wattOS isn't Mint, nor Ubuntu 

Welcome Targa.
Your question is beyond my competence.  I suspect you might need to wait till Biff gets his head up from R10 work, but perhaps someone else also has the necessary clues here.
As a suggestion, you could provide some more data.  I assume you have reason to believe the Via Nano is x86 compatible, and ideally Ubuntu compatible.
Some brief hardware specs could also help.

Out of interest : some time ago, someone overcame difficult machine specs (eg no CD-ROM) by installing wattOS onto a HDD then transplanting that HDD into the lower spec machine, with success. 

Best wishes to OnPrem, and all who sail in her.
Not least President Ron.    (Can we call off the other, media-event election now ?)

More usable ?   Depends on who you ask !

Want Xfce ?   A short while ago, someone added an Xfce desktop to his wattOS and posted his desktop in these forums.  Use Search with xfce4 as search term to find it; look for a post by Dan.     If he sees this, he might also let you know if there are any hurdles to jump in adding Xfce and removing LXDE traces. 
 

An upgrade might work, but not get what you want.
My observations as a wattOS end-user (as opposed to developer), are that :
- historically, wattOS has had less and lighter applications than mainstream Ubuntu, and has been carefully stripped-down of the "luxury extras".  (And sometimes that has meant users have needed to find a driver which might have been included in U.)  So there's quite a lot of config work in there from Biff.  I recall that this started from the U "alternative install iso" as a base. 
- recently, Canonical have also released a "core" version of U; I get the impression that using this as a base results in more building-up rather than stripping-down, but again omitting larger and heavier material.
- not least has been the integrated use of LXDE in wattOS in lieu of than Gnome/Unity.
If I've observed correctly, then an update might work (and might not), but even if it did you could find that there is a large amount of material and different configs which mean that what results is not really wattOS. 

Lubuntu is in a different position, being an official U variant.  Users would need to be able to upgrade, as a matter of course. 
(I agree with Leenie - 4 hours seems a long time for an in-place upgrade.)

If you have a clone backup of your wattOS (and hence a complete recovery option) then you could try the upgrade an see what you get.   I'd suggest first searching online for experiences of upgrading U from 14.04 to 16.04, so any major pitfalls can be avoided, but it would be an interesting adventure, no ?     :-)