Phone book limit, use of expandable memory

[jbag56]

Hi everybody. I am new to Treo, currently have BB but I am considering switching due to BB low limit of phonebook entries. Could someone advise me what is the limit of entries in the Treo (as little as I know I would probably go 750 I understand is the new or 755 I do not know the difference yet)? I need to have minimum 1500 entries in the phonebook with time probably 5000. Can Treo use expandable memory for phonebook? What is the largest expansion card it will accept? Thanks for help.