Multitasking dual core

[bobbi]

Hi, I am not a total noob at building and setting up computers but this multitasking word has been thrown about and Im a bit confused.
experts please!

Im planning on a budgey system consisting of
gigabyte s3 or ds3 mb, £4 difference only (i've never oc but may try with ds3)
core 2 duo e6400
corsaor xms2 512x2 667 (i feel the extra cost for 800mhz not worth it for me)
plus two slots available for memory when/if upgrade to vista.
palit 7900gs

firstly is this decent system? recommends.

secondly, regarding multitasking and dual core.

does the multi-tasking dual core system work by itself, what i mean is does the cpu send the threads of processing to the two cores by itself, or does the software used need to tell it what to do.
Do i need a x64 type os to take advantage of dual core?

scenario, with my present x32 xp sp2 os;
if i ran full virus scan, and then decided to play a game at same time, will each core process each application or will one core try to process both.
Will the os play the part of telling the cpu what to do?

besides memory advantage, what x64 os have to offer interms of cpu usage.

lastly, i use adobe photoshop, premiere, some cad software. will they need to dual core compliant to take advantage, or not.
if not does that mean they will just use the single core, thus ans the question will the application control the processing method or the cpu.
what about games, can they take advantage of dual core, or will they need to be programmed to do?

with this info being thrown about i am totally baffled, probably marketed for the general public as to purchase new products!

Thanks in advance, really appreciate your help

 

[TyroneShoelaces]

Here's what I do... when both apps are running (AV and a game in your example) Alt-Tab out of the game, then Ctrl-Alt-Del to bring up the Task Manager. Go to the processes tab and find the xxxxxx.exe for the two programs. Right click on them and choose "Set Affinity" Put one app on one core, and the other app on the other core.

There may be a way to permanently set the affinity for a certain program, I'm not sure.

If the game you are playing will take advantage of dual-core, though, you may not want to do this, and instead, just wait for the AV scan to finish, or shut it down early.

-TyShoe