The reason I ask is coz the girlfriend is worried that if I add more RAM to the PC... its gonna fry because of everything thats been added so far.
Silly girl >.<
Could potentially be an issue if the motherboard doesn't support the speed of ram you use, and the size of module you use; I was helping someone a while ago who was wondering why his motherboard wouldn't boot when he installed his new ram, and turns out that his old board only supported max 512mb modules across 3 slots, for a total of 1536mb.
In that particular case it didn't do any damage, but it's possible.
Also, particularily when doing many upgrades, ensure the PSU is capable of supplying enough power to power the system. If the PSU isn't rated at a high temperature (40-50C/104-122F), assume it's rated at 25C to be safe, and assume that under load/temperature it's only capable of delivering half of the rated power.
Then using a power supply calculator such as
this one find what your power needs are.