I just built a new computer for gaming, It was a bugdet build, however I was told that it was a very good built for the price. I have a Diamond 6870 1gb and i5 2500K with 8gb RAM, however until I get Windows 7 64 bit I can only use 3.17gb on 32 bit Vista. Nothing is overclocked, because I don't know anything about that yet. I can easily run Skyrim on ultra however when I use some mods I crash either every few minutes or whenever I load another area. The mods I'm trying to use are:
Skyrim HD 2K Textures Full
Realistic Water Texture
No More Blocky Faces
Improved NPC Clothing
High Quality Eyes
HD Furniture and Barrels
Detailed Faces v2
Better Females by Bella No Makeup

As you can tell they are all just for improving the textures of the game. While I play Skyrim on my Xbox I don't seem to notice anything, but when on PC I can't get over the low textures. I guess I can live without some of those like High Quality Eyes and Better Females, but I'd prefer to to keep the rest. I have used the low versions of some mods like Flora and 2k, but I was wondering if the problem of crashes are coming from other sources than just big mods. Thanks for the help.

EDIT: I'm also using the Patch 1.4(?) beta from Steam. I heard that it improves performance.

DOUBLE EDIT: I'm getting anywhere from 30 ish to 60 fps. It changes frequently (by that I mean every few seconds) outside, inside it's usually around 50-60.

First, what kind of crashes? CTD, freeze/hang/ BSOD?

You may be maxing out the vram on your GPU, or be running out of ram. Also, there are some issues with ATI cards that many people have reported. Make sure you are using the latest beta drivers for the card.

With out more info, the first thing I would try would be to copy your skyrim folder to another location, delete the contents of the default folder, and basically re-install skyrim by right clicking in skyrim in steam-> properties-> local files-> verify integrity
Then play for awhile with zero mods, and check if you are still crashing. you may be able to just delete the data folder if you are not using anything other than texture mods, or if using NMM or a similar program, uncheck all the mods.

Skyrim HD 2K Textures Full - that full version is a pig, even though the author has maximized the efficiency...it is still a memory pig. Most people running into any trouble, or those of us who like silky 60fps everywhere with a zillion other mods and shaders downgrade to the "Lite" version. Its a pretty big performance difference. By using 32-bit Vista, you are running into god-knows what ram issues, so I'd start with HD lite...if that doesn't fix it, remove all mods and build one-by-one.

If CTD means crash to desktop, yes that's it. I don't have crashes without mods, just when I have like 7 or 8 installed. So now that I know it's the 2K textures that's causing the problem, would I be able to run the Flora Overhaul mod and the Serious HD Retexture Landscape mod together? And would it help if I was able to fully use my 8gb RAM along with the 4gb RAM mod that I've been hearing about?

My game "allmost never" CTDs but after I install a Horse replacer (new Mesh / Texures) it CTDs after 10 - 15 min.

Yes Mesh and Texture replacer can result in CTD.

You should uninstall / reinstall the mods and single check each one.

Even though Skyrim HD is hard on memory, it is still 'optimized' pretty well.

Those other 2 mods can be pretty big buttons to push unless they are the lighter versions. As long as you have Vista 32-bit, you are going to run into hiccups. You are asking about your possible performance with big mods on an outdated OS...you are just going to have to experiment. Get updated, and until then I'd hold off on the big mods (what's the point if you'll be installing a new OS soon anyways?)...with your PC specs, you really need windows 7 64 to get the most out of it.