Tiger Dial-up Modem Problems


I just bought a new mini Mac with Tiger 10.4 installed. I use a dial-up and although I can connect to my ISP, I cannot download web pages (very slow) and I get disconnected after about 5 minutes (pages don't even load all the way...not even a simple Google page!). I can use the exact same ISP configuration (same phone line) on my Mac powerbook 10.3.9 with no problems at all. I have seen various posts that this is a Tiger issue, but haven't found a solution yet that works. I upgraded to 10.4.2 to no avail. Internal modem is JumpI25 V.92 with driver; MotorolaSM56K.kext(v1.3.2). Any ideas on what to try next? Really disappointed because I have always owned Macs and have never had this kind of trouble.
All I can think of is check your settings. More likely though is that perhaps the drivers aren't that great.