install multi guest os

[sabanu]

hi all,
i'm using virtual box on windows xp and i've only one guest os which is ubuntu linux.
i'm thinking that i'm going to install a second guest os which is windows 7.
but a point is wondering me.
i've 2 GB of memory in my PC.
currently, i assigned 0,75 GB memory to my guest ubuntu os.
and i'm thinking to install windows 7 and assign 0,75 GB memory to it.
after all above;
if i run only one guest os, how much memory my base os (win xp) will use?
0,5 GB or 1,25 GB?
thanks in advance...

[Sasquatch]

Memory usage on the Host varies from set up to set up. You can have an XP host that uses less than 100 MB, but also one that uses more than 1 GB. It's something you have to check yourself through task manager.

[MarkCranness]

A guest OS only uses memory while running, so if you only ever use one guest OS at a time, only 0,75 GB will be used by VirtualBox, leaving 1,25 GB for other Windows XP programs.

[sabanu]

thanks @MarkCranness.
this is the answer which i look for.
thanks again.