98SE vs Windows 2000 to prevent freezes

We use a NT based application program linked to another company via a T1. We have our people working on 98SE with 64K mem and seem to have alot of freezes. Should we consider purchasing another 64K mem or change our OS over to Windows 2000 for morecompatibility? Our link to another company on a different T1 do not experience the freezes, but they also use an older version of the application than the first group I mentioned.