What can i say, Thank you all very very much. I would say that Guru does not really express what you are !!! In general the configuration is as you described. The only mistake i think exists is that i have on the same cable an HDD and a CDROM (both in primary and Secondary Channels), but i am going to correct it today (in my desparate effort to fix it and having exhausted every possible combination) i bought a huge thermaltake tower 112 for the CPU so i will take the mobo out of the case and change the IDE configuration as you suggested (I hope the letters of the drives won't change so premiere projects will continue to work).
What is your opinion about round cables? I bought 2 round shielded cables (they insist that they are!!!!) -one very short and a longer one 60cm i think and i was thinking to use them (i bought new sata cables too you never know). Despite that i am very captious about the seagate drive. I here from times to times and especially when the computer is ready to hang the head trying to do something... a very starnge noise. The benchmarks and the diagnostics about the drive say that it is OK but i can;t tell. I have already RMA it once and today i am thinking of taking back to the shop i got it to give me a new just to be sure.
Thank you again and again and i will post the continue of my odessy soon