Instalation

I am currently running a mailserver which has mdeamon, DHCP,DNS,and a internet gateway which is my main gateway for my local area network. All on windows 2000 server with the pc specs as folows
P3 800mhz
40gb scsi hdd
256mb ram

I would like to instal linux which can runn all these services and would the computer hardware specs be sufficient enough to accomodate all the services and i would also like to knw how do i go about instaling the linux which is the best version and also i would like the detailed method of installation of linux and seting up of the services and the mailserver proxy and the other services. can any1 assist me on this.