upgrade computer

i have 1 gb ram of 667mhz. I am planning to buy a ram of 2 gb. if i go for 667mhz, then i would be wise as i shoud go for faster speed. And if buy 800 mhz and mix both rams, then also it will work at 667mhz. And if i use only new ram that means wasting my earlier ram.
I am also thinking of buying a VIDEO card of 1gb. Suppose if buy only a video card, will my computer perform faster. I dont play games, i want to use professional softwares like photoshop, flash.
suggest me wisely, what should i do

You can buy extra 1 ram of 1 gb 667mhz which will be enough for you. Buying a video card is not that necessary if your photoshop is working fine on your existing system configuration. Offcourse, video card will be an added advantage for better graphics and increase the performance of your photoshop.