First if the PC's using 4gb's of RAM are running 32 bit versions of XP they can't make use of anything beyond 3gb's as far as I know because of OS limitations. Second running the laptop while using a CRT in a docking station won't make a bit of difference heat-wise.(however it will add life to the LCD on the laptop) Third, SCSI is a waste of money in non-server applications based on every credible benchmark I've seen in the last couple years which show it being significantly out-performed by ATA-100/133 & especially SATA in applications where the HD's switch back & forth from reads to writes frequently. (Large sequential reads are a very different story)