My computer is no slouch, and I had to turn things down a notch or two because I was getting load-lag. NMC's High Definition texture packs improve eye candy immensely, but they can seriously hurt performance. Compatibility patches are necessary to get it working with things like WMK, MMM and FWE, so fair warning there. It is massive, well over 1gb installation, and because it is so big and touches so many aspects of the game, it runs a high risk of compatibility problems with other mods. FOOK started out as a compilation of weapons, but now it has expanded to include EVE (energy weapon visuals enhanced), Fellout, and Phalanx (improved companions), among many other things.
FOOK2 is good, as are Mart's Mutant Mod (adds more and better things to kill) and Weapon Mod Kits.