It won't work, and 4 gb ddr2 sticks are expensive. 4 gb total system ram is plenty, even for windows 7 64. The 32 bit windows only recognizes 3.25 gb of ram, if that is your operating system. Most g41 other boards only work with 4 gb.
I've been building my own systems for twenty years, and have worked at dell austin assemblying boards several times. Besides, as I pointed out originally, 4 gb ddr2 sticks are very expensive even if your board worked with them. It's much cheaper to change to a ddr3 board than use 8 gb of ddr2.
thanks so much xor2g for doing the research, i looked so much for the answer to this question and was only able to find people assuming you couldnt or telling me its not worth it. Upgrading my dell is turning out to be tricky