new to Windows Vista

Firstly, if I were you I'd edit your post title to something like "Should I buy Vista?" - so that you invite the right sort of responses.

Not wishing to 'rain on your parade' I think you may find the general consensus of opinion would advise you to NOT BUY VISTA as an os.

Granted, it is the new operating system but the time is still not right for choosing it over XP as there are all sorts of problems with compatibility.

From your specs of the Dell Inspiron I would suggest you will have insufficient memory for trouble free running. I'm surprised Dell accepted the 1.5Gb configuration order. You would be better equipped with 2Gb as a configuration.

The 1.8Mhz Sempron is probably the 3000+ model. I use this processor in my notebook, but to run XP. It is a rather old chip by today's standards and am surprised Dell are marketing equipment using this marque of processor in a pre-installed Vista machine.

Hopefully you haven't ordered your kit yet and can make a more informed opinion once you read the other replies.

I've found that a big issue is using a Standard User account instead of an Administrator.
I setup a Standard User account for my regular login to Vista, so that I could take advantage of the new parental controls. I set up a separate Administrator account to install software, etc.
I've found that a lot of programs don't work too well running under the Standard User account, including iTunes.

I'm running Vista (Business) and just sitting idle it uses 1/2 to 3/4G of RAM. I don't run AeroGlass, either. I'd pump up the video card to 512, too.

Navigation is a pita, but it's not that tough to get used to.

The above applies only if you're stuck with getting Vista. If not, upgrade to WinXP.

I'm 3 weeks into my Vista laptop. It's ok so far, but nothing to write home about.