I've been experiencing massive failures due to my memory, I can say that. I use a p4 pentium with 1.8 MHz, but only 384 mg of ram. I have it at the lowest resolution using no vp modifications... just baseline freespace2 installed via the open installer.
About 10 minutes into the game, it will freeze (well, slow down, move a little, then freeze). I thought it was graphics, but recently I've noticed it freezes even when staring into space.. not ship exploding or anything. This time, I noticed that the installer mentions there are some memory leaks, and as the game crashes again, I notice a "low memory" icon.
I think that's confirmation that there's some serious memory leaking going on. It doesn't affect those with gigs of memory, but for those of us "just passing by", unless I finish the mission reeeeeealy quick, my computer freezes.