sharing safe?

ok at the moment i have this setup

broadband
|
|
(ethernet)
PC
(usb)
|
|
(usb to ethernet convertor)
|
(ethernet)
Laptop

if i enable simple file sharing on my laptop, would it be safe? i tried this once before but shortly after i think i had a virus (i reformatted since then).

i use zonealarm, (on both) and xp pro sp2. and ics is enabled

also i have another question. a game i am playing between the two comps (diablo) requires ipx protocol to be installed. which i have done (on both). it works fine. as the pc has two connections (usb and ehternet) i think its safe as ipx is only on the usb (which is the laptop). but the laptop only has one (ehternet) so it uses that to connect to the net as well as playing the game. so is it safe to have ipx installed on the same connection as the internet?
note: i noticed that zonealarm did not ask me wether diablo could connect to te net! (like other progs)
------
also one last question i want to be able to connect the laptop to the net in a room where there is no pc, but there is a netconnection. but my set top box (what i have to use instead of a modem). only allows 1 ip. so how do i make the laptops ip the same as the pc???


thanks for any help with these!

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Pentium 4 <font color=red>3.2Ghz</font color=red> 800FSB (Northwood)
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