The swap space is used when the operating system runs out of RAM memory. To increase the program memory to the amount that it needs the operating system uses some space on the hard drive as an extension of the RAM memory. This, in Windows systems takes the form of the swap file, usually found on the Windows installation partition, under the name of win386.swp, for systems until Win98, and pagefile.sys on WinNT, 2k or XP. This pagefile is created dynamically ( windows takes as much space needed) or its size can be set by the system admin. However, if it's set dynamically and a user consumes all the space on the system partition, there will be no more free space for the swap file, which causes the system to run very slow and eventually crash. Also, this file can be sometimes very fragmented, which can cause slow acces to it.
That is why *nix systems have a different approach: instead of a swap file they use a swap partition, created at installation time. This way, the problems enumerated above are avoided. A thumb rule for the size of the swap partition is twice you RAM memory. However, if you have 512 MB of RAM, 512MB of swap will be usually more than enough and if you have 1 GB of RAM, I think the swap partition will never be used
. Of course, except for the case of some huge simulations.
You should start with Mandriva Linux, it's more user friendly, or, if you want to install software like Cadence IC you should go for an older, 2.4 kernel based version, like Mandrake 9.2.
Good luck!