i recommend you do get the E6300. here are numerous apps already that benefit greatly from two cores, and even if there are still games that dont use both cores, you can do a lot of stuf in background, and the E6300 isnt that expensive.
If you get a decent board, you should be able to clock it to around 3 Ghz without problems,maybe youll want a stronger cooling solution then though ( I heared the Scythe Mine was good)
As a board I recommend a P965 chipset board, because the 975 are too expensive.
The Gigabyte S3 seems a good choice at marginally more than 100 euro
Check for compatibily lists between RAM and P965 though.
If you are going to overclock it, you should consider buying DD2667/800 Ram though because there are no deviders on these board that slow down the RAM.
If your not overclocking you can get a cheap AsRock board and use the stock cooler.
As Lex mentioned 1 GB RAM is a bit on the short side (Vista, future apps). I recommend 2 GB so youre able to run dual channel. but you can get 1 GB now, and buy 1 GB next year (because prices are high atm)
The Gf7600GS is a really slow graphics card, but its passive I think.
A card with an outstanding price/performance ratio would be the 7900GTO (but i think its no longer available) at around 230€, or 7900GS at 170€.
the 7900GS is probably around 2 times or more as fast as a 7600GS. so i guess its worth considering the price difference.
edit: oh just saw you dont plan on graphic intensive applications.
then the 7600GS is fine I suppose.
but why are you upgrading from a 2,6 Ghz P4 ? isnt that enough for your needs?
)
ambi 
