Big enough flash drive would work. Or you can turn on file sharing and copy them over the network either via ethernet or WiFi. Gigabit ethernet would be the fastest option by far. But if that's unavailable WiFi will work. I don't know how "old" the Dell is or what router is being used but I copied some 7,000 songs over WiFi from a Toshiba to my iMac using WiFi (802.11n at 5GHz) and it went fairly quick. If it's going over 802.11g it'll be pretty slow. But will work.
An 8GB flash drive would probably hold that many songs if you don't want to go the network way.