Just keep in mind ...the faster they go the more heat they generate and the more wattage they use. Not sure how well designed the Dell case is for heat dissipation.
I would like to upgrade my current ATI Radeon x800 xt video card, I believe it is using PCI-E slot with 350 watt power supply. I have Dell Dimension 8400.
I was recommended by Dell to upgrade to Nvidia 8800 GT since it only requires 425 power supply and existing 350watt should be able to handle it.
1)is that the best video card I can upgrade to for 3d gaming?
2)I have seen some 8800 GTs on Newegg over clocked to 700MHz Core speed, do they require more power is it safer for me to go with regular 600Mhz?
you plan on anything faster than a 8600gt/2600pro. if the card has a PCI-e power plug, it probably can't deliver the necessary voltage.
personally, i don't like tom's list because it gets out-of-date quickly and has 'optimistic' pricing. for example, in the US the absolute cheapest 8600gts is $120, not ~$100. for $130 you can get a 8800gs or hd 3850 which are 50+% faster.
Hoarding photos on your phone?
Those picture are hogging memory and could be slowing down your phone.