[Yum] total yum newbie | RH 7.3 box | # packages?

[Johnny Canuck]

Greetings -

Various colleagues suggested trying yum to manage package upgrade on my RH 
box (7.3). Since RH went corporate, up2date doesn't work for 7.3, and I was 
looking for an alternative. Tried apt-get, with little success. Installed 
yum, and am in the process of trying it out.

So, I ran yum check-update. and after an hour of watching it continue to 
download package after package (whether I wanted them or not), I kill the 
process, and tried something more direct: say, update one single package.

So, I tried yum update grip

But, yum once again resumed downloading package after package, many of 
which I know for a fact aren't relevant to updating grip.

So, my interpretation is that yum basically wants you to download EVERY 
package there is for your box first, before you can do anything else? I 
suspect this can't be true, but don't know why it seems to be doing just 
this for me.

What I liked about up2date is that it compared the RPM's in the RPM db with 
changed RPM's, and only 'downloaded' those I needed - I'm guessing yum is 
supposed to do this, but sitting here in my second hour of watching 
packages download makes me wonder.

What obvious thing am I missing? Newbie question, so set flame-throwers to 
'singe' only. :-)

Thanks in advance!