*Is Wilderness a pre-mod to Giants?
*Which is your top-5 desert mods to alter Morrowind?
Wilderness is a stand-alone mod. It doesn't require Giants (though the two fit together very well). Wilderness adds mostly non-hostile creatures to the game. It's a wonderful mod, in my opinion - but it can be demanding on lower-end computers.
If I had to pick just five mods (nearly impossible) I would pick these:
1) http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=6173 by Westly. A new face and hair for my character is essential for me. I can play Morrowind without a lot of mods but I need a new face and hair for my own character. For this I usually use Westly's head pack (though in my current game I'm using http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=6665 instead).
2) http://lovkullen.net/Emma/kids.htm by Emma. This is my all-time favorite Morrowind mod. If I am going to use any mod in addition to a head/hair mod for my character it will be this mod. To me, Vvardenfell just seems depressingly empty and lifeless without children. Without the sight of girls skipping and boys getting into fights the world is just too unrelentingly grim for my taste.
3) http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=4699 by Fandorn Delavie and the Wiwiland team. This is kind of a 'prequel' to Emma's mod.
In my opinion both Morrowind and Oblivion are distressingly anti-social games. There's little opportunity for the player character to show affection. The player character mostly kills things. This is a serious limitation of Elder Scrolls games in my opinion. The Romance mod helps make Morrowind a little less one-dimensional in this area.
4) http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=1695 by Hoghead the Horrible. I feel another limitation of Morrowind is the lack of non-hostile creatures in the game. I find it a little wearisome to have to fight practically everything I encounter everywhere in the game. Hoghead's mod adds some much-needed life to the game world that does not psychotically attack the player on sight. It's a good alternative to the Wilderness Mod for lower-end computers.
5) http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=2786 by Abot. Does the same thing as Hogshead mod, except above ground.