Security for wifi usage

I have been using a regular wired DSL broadband modem in my Compaq laptop. I shall be travelling, and am looking at iPass ( http://wireless.tataindicombroadband.in/wireless/wifi.html ). Since I am a bit confused about the security issues which may have to be addressed now, I am requesting for guidance.

I have a Broadcom 802.11b/g device.

My current OS/security setup is as below :-
a) Win-XP SP2 (completely patched, vetted by Secunia)
b AVG AV/AS free 8.5
c) ZA firewall free 7.0.483
d) Sundry utilities/protection software : Ccleaner, Spywareblaster
e) Safe browsing habit

My first query : In the settings for my wireless network connection, there are the following choices :-
a) Any available network (access point preferred)
b Access point (infrastructure) networks only
c) Computer-to-computer (ad hoc) networks only
Choice a) is selected by default. I presume that when I am using the iPassConnect dialler, these choices are irrelevant. Are these choices relevant only for a free wifi hotspot connection?

My second query is about the security aspect. Do I need to activate WPA/AES, and if so, how? Also, I read somewhere that SSID broadcast should be disabled ... how is that done? More, is it necessary to have any security key / passphrase ... or, are the iPassConnect login credentials (username, domain, password) good enough?
Or, are these security issues relevant only for a free wifi hotspot connection, and not required when using iPassConnect dialler?

Thanks,

Edited by abanerji, 15 November 2009 - 08:08 AM.

Corrected the link http://wireless.tataindicombroadband.in/wireless/wifi.html