768mb or 1gb for compaq v2000z

i'm picking up this laptop. 128mb RAM will be dedicated exclusively to the gpu. thus with 1gb i'd have 896mb or so left to system, and with 768mb i'd have 640mb left to system. now, i'm asking myself: would i ever see the difference between the two? it's not supporting dual-chanel, so having different size sticks is no problem. in my mind, i'd never notice the difference. am i correct? would the difference be important? one thing would be that if i go for 768mb then there would be two different types/brands of mem sticks. for 1024mb (2x512mb), the sticks would be the same. the laptop i'm getting comes with 256mb, and obviously i'm going to buy more RAM aftermarket. oh, mainly this lappy will be used for web surfing and basic productivity stuff/multitasking. i will also play an older game once in awhile.

specs:
turion ml-28 1.6ghz 512k L2 cache (another question: would the upgrade to 1mb of L2 cache make an important difference day to day? it's a $25 upgrade)
radeon 200m gpu (128mb ram will be locked into use for gpu)
4200rpm 40gb hdd (will consider upgrading: important?)

thanks

btw: decreasing noise/heat is important. if the extra RAM would help than it's worth it to me.

I'd upgrade everyone of those things you just mentioned. More RAM is always good, a 4200RPM harddrive is dog slow, moving to 5400 is a noticeable difference. The difference between 5400 and 7200RPM isn't as big tho. More cache is always good to have as well especially at $25.