The best way I know to stop popups (in XP & win2000) is to add comments to your C:WINDOWSSYSTEM32DRIVERSetchosts file.
just copy & paste below:
# Copyright (c) 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by #Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP #addresses to host names. Each
# entry should be kept on an individual #line. The IP address should
# be placed in the first column followed by #the corresponding host name.
# The IP address and the host name should be #separated by at least one
# space.
#
# Additionally, comments (such as these) may #be inserted on individual
# lines or following the machine name #denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
127.0.0.1 localhost
127.0.0.2 sbad.foxsports.lycos.com
127.0.0.2
www.celebritywonder.com
127.0.0.2 doubleclick.com
127.0.0.2 ads.x10.com
127.0.0.2 yimg.com
127.0.0.2 us.a1.yimg.com
127.0.0.2
www.timeinc.net
127.0.0.2
www.imglmb1.com
127.0.0.2 ad.doubleclick.net
127.0.0.2
www.zdmcirc.com
127.0.0.2 ar.atwola.com
127.0.0.2
http://servedby.advertising.com/
127.0.0.2
http://www3.bannerspace.com
#end
I know there is a way for this to be done in win98 too I just can't remember right now.
I use it, it works! If you start getting popups from a new source just right click on the offending popup and copy the address and add it to the hosts file after the 127.0.0.2 part.