I dont know how heavy assemblies you have, but you can try to open assembly in "large assembly mode".
I was used to open few subassemblies in background before opening main assembly, and then close the subassemblies once main assembly is open.
I hope one of these tricks should work, else you can consider upgrading your system !
By the way, which version of Solidworks are you using, because in SWX '15 they have reduced the file size considerably.
As for SW is concerned Nvidia Geforce graphic driver is not supported.
Also try opening the assembly in "large assembly mode or lightweight mode" to open the model with much ease and then switch back to resolved once the model is been opened.
By the way is the 8GB RAM used as a single chip or multi chip. If multi-chip try to go for single chip RAM which could be much stable than before.