Okay so I bought a Zoom h4n and have been recording some electric guitar with but I'm having a issue:
The clarity is amazing but the quality isn't quite professional.

I'm using:
A Marshall MGDFX100 1x12 (****ty amp. really poopy sounding mic'd)
A schecter blackjack. Seymour duncan JB and '59 pickups
Really old strings. (About 2 months old. They're rusted and have lost their new string sound. This is probably a big contributing factor to my quality)

Listen to the one called Quality Test
The guitar riff kicks in with the actual recorded guitar track, then I play the riff, and then it goes together so you can hear how the clarity sounds.
I recorded an example using guitar tracks from Lamb Of God's 'Again We Rise'.
Listen to the quality and see how they both have the same clarity but mines a bit lower quality? I know in studios they use many mic positions and different mics to get the right sound but I want that clean and high quality polished sound.

So: Why is this exactly? That guitar recording is super clean, super polished and sounds great. Can I achieve this with my Zoom H4n? Is it due to my amp and strings that it sounds this way, or are guitar tracks usually sound this raw when recorded and are polished up during mixing to sound the way they do?
I had a similar problem like this when I was recording someone at the studio. On any project you do the tracking is not going to sound exactly like what you want. Your amp and strings and mic are all factors in the recording process. However, on LOG's stuff they use 3000 heads and expensive mics and are running through an Pro Tools HD system recording at 24 bit 96kHz probably. The Zoom does the same bit and sample rate but the mics arent quite as good and are in the X-Y pattern and that doesnt leave much flexibility. I think you would have better luck using the Zoom as a device to record ideas or do field recordings for a sound fx library but as far as getting those sounds you hear on records I dont think so. Also the over all sound on a mastered CD is way different that a mixed song and a mixed song with EQ and compression and verbs and everything is way different than a raw tracking. If you are interested I have home studio and also work at a small professional studio in Louisiana, you can email me one of your little diddies and I can send it back with a few different mixes if you like. I run Pro Tools 8 and you can check my profile to see my studio gear. Anyway good luck on achieving that sound. co.mark@yahoo.com is that address if you are interested