DazDaz, sounds like it's to late for you, however......
As a general rule get to SP2 as soon as you can, it's more reliable and includes a lot of security fixes, but still apply all security fixes from MS as they are issued.
As with all upgrades avoid the standard problems by reading the instructions! The most common diagnostic on an IT help desk is "user error" and the easiest fix / avoidance is RFM ... Read the
Manual.
A bit like flying
regards
(IT Director with about 2,500 desk tops, and worse, 2,500 users
)