all intel x64 systems are capable of being 32 bit. also almost all non-netbook laptops are x64 systems now (and have been for many years). however, if you run 32 bit, you can address less RAM. so. have fun! :(
my primary computer is a notebook and I routinely run processes that large (vmware, mathematica, matlab, IDA, binnavi, my own programs, etc).
"why do you run these programs on your laptop instead of sshing to a server somewhere?"
sensitivity, responsiveness, I don't always have internet, the hardware can do it (8-16GB of RAM in a notebook is almost commonplace)