This is about choosing a distro(again). Until now I had a Mandrake 8.2 and RedHat(8.0 and 9) and soon I will install Slackware 9.1. I just need to know witch one of these do you think is suitable for programming in C\C++, JAVA, assembly, Pascal … For now I am not interested of network tools because I can’t implement them(I don’t have a network) so I am interested just for programming.
And another question:
On my hdd I have:
First partition- NTFS partition (primary) – for windows XP
Second partition- boot partition (for grub)
Third partition- ext3 partition for RedHat 9
Fourth partition- swap partition for RedHat 9
If I want to install slackware I will resize the NTFS partition but how can I install slackware without affecting the grub configuration or others partitions?

Thanks!

Don't forget about the primary/logical partitions. If you have all primary ones, you have a problem, because only four are allowed (you can put way more logical partitions, see the partition howto @ www.tldp.org ).
Note that adding a new partition between others will change their numbers. The ones after it will go up. Example: You had hda1-win,hda2-RH,hda3-swap. Squeezing another in will make you end up with hda1-win,hda2-slack,hda3-RH,hda4-swap. As you can see, RH is no longer hda2, it's hda3. You will have to edit Red Hat's configuration to reflect this, ie edit the /etc/fstab file and /etc/grub.conf file. Choose not to install lilo with Slackware, then you can add an entry for it in grub.

i don't think the difference of distros will affect the programming thingy,unless in terms of speed or perfomance. as i do feel the speed is faster when i open jave ide like netbeans in slackware.

As a programmer I definately agree. Slackware is the fastest distro I have used.