Indeed Good news, Thomas. Your 540 has no provision for a memory card, but evidently is one that started out life with 4GB of memory. Your serial number starts with "RZ", correct? That's how you continue to get maps. The smaller memory (2GB) versions of the 540 (serials starting RW and RX) don't.
Unlike yours, my 2GB 740 Live (serial WR) is on the EOL hit list. I guess they changed their minds - and never updated the list - since I can slide a memory card into mine to make anything fit that I could possibly need.