I have router 'BEFW 11S4

Question

I have router 'BEFW 11S4 VER. 4 works great. We use "XP' Have 2 other laptops on our secure net. Just bought a new Sony 'VIAO' with "VISTA' and tried everything to log on to our net...says signal good but limited connection and cannot get to Internet. Went to Linksys.com/check and made new file on stick...new system says that file is not readable??? What do I try? H E L P !!! Dave