Windows 7 ?

You say your tag shows up, and you did not install it yet, so there are files of your Virtual store who gets loaded.System is using files who are on differnt places, if you install in Program Files.
Normal installation up to Windows XP :

C:\Program Files\Quake III Arena
-------------------------------------------\baseq3
-------------------------------------------\excessive
-------------------------------------------\excessive\conf

With Windows 7 you are going to have a different set-up when placed in c:\Program Files(x86)
Windows 7 doesn't like it when you want to change data in this structure, and you change data every time you play a map, look at the q3config.cfg in your excessive-folder.
Windows 7 places those changing data-files in the directory-structure :
C:\Users\Thor\AppData\Local

As you see, changing files are away from the Program structure. Making it harder to maintain your files. Where to put your maps ??

It also depends on how your fs_homepath and fs_basepath is set.

To make it understandable, and easy to maintain, i advise you to make following installation (Or Copy action)

First create a directory into the root C:
C:\Games
Under this directory you install Quake3

C:\Games\Quake III Arena
-------------------------------------------\baseq3
-------------------------------------------\excessive
-------------------------------------------\excessive\conf

When installed in a different directory, Windows will allow you to keep those changing files in the same directory-structure you are familiar with.
So you definatly know for sure where to put those maps

hey, what is ioquake?

i have visit theire website but i still don't get it, because it's still q3..

Why don't you just find pak0.pk3 and download 1.32 install and play?

@shadow: Imo problem to connect to hiszy was about some mixture of e+ pk3s and pk3s in baseq3 folder. I had exactly the opposite problem that I could not connect to hiszy except i thrown out pk3s and other way round.