still learning

I have 2 routers a wireless netgear mimo-g rangemax connected to 3 win xp home edition pc's and the 4th ethernet port is used to connect to my cheaper belkin wireless-g router (100ft away with cat5 cable), which is useing 2 ethernet ports on the 2nd router- currently my PC i want to make the server and my xbox 360. I have had problems file sharing locally with the other pc's and noticed the subnet address is weird for the first netgear router (which is connected to the cable modem) it is 255.255.248.0 i tried to change it to the same one on my belkin and it wont allow me, it only gives me drop down options like 255.255.255.0 ect.. currently i am running windows xp pro and ubuntu dual boot on my pc (the forth one i want to make a windows server 2008) any ideas on why my file sharing is not working from my belkin router to the netgear? i noticed also the default ip when i reset the routers is diffrent 192.168.2.1 and 192.168.1.1 could that cause a confliction? Do i need to put the cable modem and netgear router in my room where the server will be in order for the local filesharing to work with the other 3 PC's and my xbox 360? Just got a Western digital My Book 320gb home edition usb drive that i was trying to use on my PC to file share with other PC's on my local network, and use it so they can see it in there network places to backup their files too and to retreive files from and it does not work. I called western digital and some dude named Joe with a thick indian accent told me thats because its not a network drive it is just a usb drive, i will have to walk the my book to each pc in my house to copy the files or retreive them. He also said that if the external drive does not have a ethernet cable plugin it will not work as a network drive, like how i want it to work. That sounds like total crap to me, i dunno, i have a 40gb internal HD i have a special cord that connects IDE to the back of the drive to USB which plugs in my PC and i can share that on my home network.. please help!!! lol BTW; Darren this is UN whatwhatbia from youtube i found your site from there. I plan on formatting my PC and installing the windows 2008 server because alot of business use it, just to learn how for a month then i will install a Debian server. I would like to config the windows server to use my other PC's in the house as clients , create a workgroup and active directory, and need config help , maybe tutorials you may have i dunno, thanks!!!

all of my gaming is done on my 360