System slowdown despite mem upgrade

Hi

My system seems to be much slower after I added another 1GB of memory

System info
Dell Inspiron 6400
Duo Core 166
WInXP
Previously 1GB mem now 2GB after upgrade
Avast and Comodo

Since I jacked up the memory the system seems slower during/after startup. The desktop takes longer to load and windows have a longer delay when attempting to open. The browser/window that would take a second to load now takes longer.
Once everything has started up things are (presumably) ok. It just seems like the startup has gotten much slower.

Could this be due to Avast or Comodo as well? I had them before when my RAM was 1GB but never had this problem

Any advice/observations?
Thanks in advance