Vista 64 Tweaks: Are they necessary?

I have Vista 64 coming in a few days and I wanted to know something in advance. With WinXP Pro I am used to having to install the OS and perform various tweaks for performance or security (disable services, edit registry, etc.) I have often found myself uninstalling too much when I do NLite installations, and eventually I came about tweaking once and then just imaging.

My question is this: Will I see and performance gain that proves to be necessary so that my system runs as smoothly as possible? Or can I just install everything and use it when needed?

I will be running a e6850 with 4gb pc-8500 on a gigabyte ds3r. I would hope I could install everything and then just tweak it over winter break. Thanks for any tips!

I turned off a few services I don't really notice a difference though I kind of just did it because tweaking is fun lol.

Yea I know what you mean... after a while I became borderline OCD with tweaking XP... even on my mom's pc who doesn't use it for anything more than email...