Parallels & Upgrading

I have a stock plastic macbook from 09. 2 gb ram 667 and 2 ghz core 2 duo on last version of leopard. Parallels runs OK but my apps load slow and take long time switching, after a day or two especially going sleep/wake up cycles VM starts slowing down a lot need to reboot it.

Will upgrading to snow leopard and 4 GB ram solve this problem? This will set me back at least $200 so I need some good info to make a decision. I need to buy new RAM, snow leopard and new version of parallels plus do a complete backup and waste probably a day doing the upgrade.

Thanks, but I don't think I want bootcamp, the time it takes to switch back and forth is such a headache that I might as well use windows 100% in that case. There is only 1 app not even very CPU intensive that I need to run and of course MS office, I am not paying twice for the mac version!!

Any experienced parallels user? Parallel works nicely especially with spaces, but after a while it really bogs down my whole system just idling.

Yeah I'm using XP, 512 MB allocation or auto I think. My disk thrashes very badly when the VM is just idling. I listened closely and could hear the disk reads, my page in/ page out ratio is about 50%. I get that swirly thingie all the time just switching apps. All it takes to bog my system down:

Parallels with XP conservative RAM
Safari
Firefox
Xcode
Interface builder

I only need XP to run developer studio 2005 and MS office.

Not sure if I'm ready to upgrade to snow-leopard or parallels 5, can you tell me how much better % wise? I've decided to stop being a cheap ass and to upgrade to 4 GB. I find myself talking myself out of launching parallels whenever I need to do something in windows. This is not good.

Oh yeah my iphone software developer subscription expired, another $100
Just bought applecare $200
4GB ram $100
snow leopard parallels ANOTHER $100

These $100's start adding up!

Let's hope no new battery... that would be yet another $100!