Should I upgrade to 4.9?

[Dragoncrest]

	I'm upgrading all my workstations to 4.9 tonight, but I have a small mail 
server (p120 with 120m ram) that's running 4.8 that does nothing more than 
fetch mail, sort it, scan it, then deliver it locally for me to pick up at 
my leisure.  I'm wondering if it would be in my best interests to leave it 
at 4.8 for right now or go ahead with the 4.9 upgrade.  The mail server is 
my only mission critical machine right now, so that's why I'm asking 
this.  It's the only box I can't afford to have go down.  Any help or 
suggestions is welcome.  Thanks.