Networking between a XP, XBOX 360, & vista - over a wireless route

[NFL_Demon]

OK... Before anything is asked, the follwing is for advanced networkers that know alot and any answer would be GREATLY APPRECIATED.

Before I ask anything here is my hardware, computers, etc:

Dell XPS M1710 Laptop

==Running Windows Vista 32-Bit

==Wireless Connection

EMachine ( Windows XP )

==Connects via ethernet cable

==Currently only computer with printer installed

==This computer is what the X1150 Connects to

==Latest X1150 Driver installed

Lexmark X1150

==Connected via usb to EMachine

==No ethernet cable ports

LinkSys Wireless G Router

==No USB ports

==No security besides MAC filtering

==Latest firmware

- XBOX 360

==Wireless connection

==Latest Update

PROBLEMS:

1) I would like my network to have better security.But conflicts exist between the 360 and XPS.

2) I would like to be able to print documents with my XPS to the lexmark.

I made a diagram of all connections here: