Re: overloading ram?
Go to the task manager (ctrl+alt+del) and see how many processes you are running. The number should be at the bottom.
It should be completely fine though, Firefox uses a good amount of memory, and so does Windows Vista on it's own.
My Computer: eMachines T5226 - Intel Pentium D Dual Core @ 3 GHz - Diamond Viper Radeon HD3870 OC Edition with 1 GB GDDR3 VRAM - 4 GB PQi Turbo DDR2-533 RAM - Corsair 650W PSU with 52A on single rail - TSSTcorp DVD-DL+-RW combo drive - Lite-on 52x CD-RW burner - Creative SoundBlaster X-Fi XtremeGamer - Logitech z5300e speakers - WinFast TV Tuner - Vista Ultimate 64-Bit. eBay name: Flightsimboy304