Tracking memory leak

Is anyone aware of Freeware, Shareware, or eval software that can log how much memory is being allocated to Windows, running applications, and drivers? Our situation is this, vendor writes sever based application for Windows 98 production machines that drives three printers, one handheld scanner, and also utilizes some third party barcoding software. Within 20 minutes all physical memory is used up, and befor e the shift is over the system requires a dirty shutdown and reboot (which the MS access database doesn't like. Any software out there whuch tell me who isn't letting go of memory when done with it?
Thanks