I decided to revisit RE4 on PC and see how far the fan-base has been able to enhance the visuals. For those who don't know, the PC version was a port of the PS2 version, which was extremely flawed compared to the Gamecube version. Namely, polygon counts and textures were cut in half, and a lot of the environments were trimmed down in subtle ways, and various other effects were either removed or downgraded. Also, all the cutscenes were pre-rendered, instead of realtime like Gamecube offered, which meant they had compression artifacts and your unlocked costumes were never shown.
Well here are the essential mods I've found that improve the visuals without making drastic changes.
Resident Evil 4 Texture Patch v2.0, by Albert
This mod made massive progress so quickly, because of the simplicity behind it. Basically, Albert found out how to cut and paste the textures from the Gamecube version to the PC version with much ease. A job that Capcom should have been able to do originally. You'll notice just about every texture in the game looks twice as good, just like you remembered it on Gamecube. It's fantastic. Albert later went through and further improved some textures that still stood out. This is a very self-contained, and perfectly compatible mod, and should be the most important one to grab.
Enhanced Environment 2.0, RE4 texture improvement, by Cerberus
This is a much less vital texture mod. A lot of people swear by it, but when I installed it on it's own, I noticed that it didn't improve quite a few textures that Albert's does, despite being much larger in size and claiming to contain Albert's textures. It's recommended to install this on top of Albert's, as it does do a pretty good job on the environments, as was the initial goal. You can live without this one however, should you need the storage space.
Hi-res Eff/tpl Textures Replacement Pack 1.0, by Albert
The most important feature of this mod is that it re-skins the menus and fonts of the game, as well as adds custom button icons to match your controller. It does a flawless job of fixing up all the low-resolution console GUI objects. There's just one big catch to this mod. It requires that you run the game through a loader exe every single time, and it adds about a 15 second boot time. Kind of a pain in the ass, but if you tend to play games for long stretches of time, you won't mind. I don't though.
Re4 Ps 2.0 Bloom Mod, real bloom, by cdiddy7
This mod tries to enhance the lighting to resemble the lighting engine seen on Gamecube. The original UK and Asian releases of RE4PC actually had no lighting engine at all, but a later patch, and NA release, incorporated a simple lighting engine. This mod tries to take things a step further, but you may find that it goes a little too far on the bloom. Also, the menus will be affected by it and bloom as well, even the white font on black backgrounds. Basically, it makes the in-game graphics look better overall, but makes the rest of the game look a little out of place.
Improved Cut Scenes V2.0, by Sp00kyFox
On top of being stuck with pre-rendered cutscenes, Capcom did an absolutely terrible job of recording them. They all had awful compression artifacts because they were using low bitrate MPEG2. They also used a crap deinterlacer. Well, Sp00kyfox fed the clips through some AviSynth filters and did a great job of restoring them as best as anyone could, and then he encoded them through the best codec current available (arguably), x264. This requires FFDShow or else the clips won't play in game, but if you are of the many who just use K-Lite Mega Codec Pack, you're already good to go. The cutscenes will still look low resolution compared to your high resolution graphics, but until someone figures out how to mod in the realtime cutscenes from Gamecube (there was some progress on this a while back) this is your best bet.
Laser Tweaker, Change transparency and color, by St.Vampyre
By default, the laser sight on your weapons is entirely too bright and thick. This little mod lets you turn down the opacity and shrink the laser dot. Simple, but important.
Oh and here are some pictures I took myself.
More mods here: http://z6.invisionfree.com/Resident_Evil_4_PC/index.php?showtopic=573
LOOK WHO CAME: