I recently decided to play again the game but this this time using mods to enhance the gameplay.Well, as I did with Skyrim,I went to NexusMods and searched for all the potentials mods that I might want to use.The problem is that after searching for a while I got confused by the massive amount of mods and I am not sure which mods to use(I even checked some articles regarding to this but I they weren't enough).So I would like to ask which are the best mods(gameplay,graphics,face-body textures,weapons,armor,sounds) to enhance the game experience(more than the current one).

I have this specs:Intel Pentium Dual Core E2200

Ati Radeon HD 5450 1GB

2GB RAM

Also to note that I am running Skyrim(lowest settings) with around 80 mods and I used to run Oblivion without having any lag(don't know how much FPS I had since I never checked it back then)

I would stick with a very limited number of mods since with those specks. You are not going to gain really anything with the texture mods, since it would just be better to play at the highest setting for Oblivion.

For the faces you can use Oblivion Character Overhaul which improves the faces by quite a bit.

I would get OBSE at http://obse.silverlock.org/ since quite a few mods depends on that.

Get the unofficial patches to help fix bugs that still remain from the last official patch.

You might want to have a UI mod such as Dark UI Darn, Darn UI, BT Mod.

You might want to use a different leveling system if you prefer more the way Skyrim Levels than you might like Realistic Leveling mod, For that mod you would need Fundament and MenuQue to be installed. But there is also Oblivion XP which makes the leveling more like a tradition RPG by getting XP when you kill enemies and xp from miscellaneous tasks.

There are some large overhauls such as FCOM but I doubt your system can handle it.