Modem not working after system upgrade

Hi, i had a computer having 800 MHz celeron, VIA FR33 Motherboard and 256 MB RAM, i had 56K Modem of Intel HAM plus V.90 (Ambiant technologies ) now i bought a new computer having 2.66 Ghz Core 2 Duo , 2 GB Ram and Intel DG31 PR.
i installed that old modem in my new system . Drivers are installed but when i call to connect to internet the Dial tone ( like Pressing numbers on phone ) is slow then when i used it on my modem on my old system.
most of times , it does not connect to ISP. at once it connects and the Connection Status Dialog reports Errors in Receiving packets.

is this due to Processor as it is 64 Bit or due to Motherboard. the modem works fine on my previous system.