Concern due to drastic transition

Hi:
Thanks all for the responses to my previous post, 'M.S. Office 2007.'

Now, I have another question as reading one of threads on this board
concerning impact due to drastic change.

The PC is pre-loaded with XP Home Edition and 512 RAM with less than 100 GB
that I purchased about 5 years ago. It's been running good, but I've been using as a
back-up PC because I purchased a brand new PC with Vista recently.

I need to install 'M.S. Office 2007' on both PCs, XP and Vista. The Vista is no worry,
but XP, I started to concern because whenever I install new stuff, either hardware or
software, the machine getting sluggish, although it's getting back to normal after few days'
use.

My question, .... whether it's possible for me to install 'M.S. Office 2007' on XP without
drastic impact? If does, what precaution should I take to avoid it?

Your imputs would be greatly appreciated.

Thanks,

.