depending on your version of EvoX Dash and the bios you should be able to put in a 137 gig (plus) hard drive in your xbox...
www.xbox-scene.com will help you out with the tutorials and to download the bios you will need to use mirc and a mirc or packet search engine....(use google to search for an irc search site)
im wary of updating the bios on my xbox so i settled for an 80gig maxtor hdd and its superb...without the latest bios upgrade u can use a 120gig drive (it makes an F: partition.......on the new bioses the 120gig is the F: partition, the remainder space is G:)