Dell Dimension 4400 wireless connection

Hi I am trying to help a girl locally with her wirless set up. ( Dell Dmension 4400 & laptop ) I installed the pcmia card and software on laptop ok. Then set about configuring the Linksys wireless router connected up broadband modem to internet connection in router, attached another ethernet cable to 1 of 4 vacant sockets to connect to rear of dell, however can only see 2 dial up modem small connections? There are 4 usb conmections 2 front and 2 rear. Is there a way round this, or have I missed a trick somewhere?? Or does she really need usb wireless, are there adaptors?