Enterprise Storage Hardware

I'm also curious as to some suggestions on forums really geared towards server hardware discussion. if you know any good ones, please let me know

anyway, here's the situation:

I currently lease my servers. I'm planning on switching to colocation. three primary functions need to be met:

1) web server
2) mysql server
3) mass storage

I'm contemplating the best way to do this. price is a concern but I'm willing to pay more if it's warranted.

would it be a bad idea to have the mass storage and the webserver on the same machine? ie, take the web server box and just throw in a SAS/SATA RAID card and put in the extra disks. it'd obviously save in overhead costs.

if I do put them on one box, should the OS be booting from seperate physical disks from the rest of the storage?

if I don't put them on one box, ie, the web server and the storage server are seperated, what would be the ideal way to connect them? just ethernet/LAN, through a fibre connection, etc?

and that brings me to another question... why does SAS have external adapters if it's not supposed to be used to directly attach the array to more than one box? can it be used this way? is there a reason it shouldn't be?