I'm thinking about remastering my old songs.
The main problems is that most of the guitars sound quite synthetic. I'm not sure I have time to to record them again so I wanted to know if you knew how to fix it. Maybe play with the Eq or even using a plug-in like Amplitube so give them a more realistic sound.
Any help would be extremely appreciated.

             > Iszil

Best to re-record it Is, you can only get good results with sound if the source is good, you may improve it a little, but it would be hardly noticeable.

When you say synthetic, is that kind of digital?? I suppose you could run it through a tube/analogue plug-in.
I think I have one in Adobe Audition, I downloaded it somewhere, free trail. I'm sure there are loads available if you google it. I remember vaguely speaking with Marino that FL has this built into the software, I cant remember what it's under, but if you PM/email him I'm sure he would be able to tell you. I think it's under compression.
I've seen some musicians run their recordings through an analogue Tape machine or OLD VCR, some of them have HI-FI and actually record the width of the tape. In fact I used to have one, When I played my Music videos through my Technics Hi-fi it was the best sound I've ever heard, seriously, it was so rich and warm.

These days I record all my Audio through a Tube/solid state class A pre-amp, it's only a cheap one, but it sounds great. Although I use a pod for my Electric guitar, and literally just started to use the combination of POD and my Tube pre AMP for Bass, The Bass sounds awesome.

EDIT** Send one track, I'll run it through my gear, see how it turns out, can't promise any miracles, as I said the secret of getting pro results is the quality of the recording at source.