i'm posting as if when you said "mbr at hda1" you meant "boot partition at hda1"...
dbkluck is right, the usual way is to have windows on hda1 and not on hda2... but it should work fine anyway...
i think you'd wanna put linux after hda2, so delete everything after that (hda5), and then, in the free space, create your new linux partitions as, for example (mounted at the given locations):
/dev/hda5 ------> /root
/dev/hda6 ------> SWAP
/dev/hda7 ------> /home
you'd probably want to keep your boot partition also, you could nuke it and set the way for lilo or grub, if you want...
/dev/hda1 ------> /boot
the only partition you shouldn't touch (as in delete, format) is the windows one... of course you could mount it somewhere like /mnt/windows if you want quick access to it from linux...
the sizes you assign to your partitions are up to you... i'd suggest 2 - 7mb for "root", depending on how much software you plan to install... 200 - 1000mb for "swap", depending on how much ram you have... the rest for "home"...
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i suggest if possible, use the reiser file system for root and home.
it's VERY nice (lots of advantages over other filesystems).
if red hat 9 doesn't do riserfs out-of-the-box (i suspect it doesn't, but i'm not sure right now) and you really want it, you could use mandrake linux, it comes with support for reiserfs and xfs (from silicon graphics) and many more... it's installer allows partition re-sizing (even NTFS), and it's found by many to have the friendliest partitioning tool.
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i have nothing against ext3... i think it's a perfectly decent file system. the only thing is that it's really just ext2 with a journalizing layer on it... it's not a "natural" journalizing file system.
it sucks when, like, for example, you have to wait 2 or more minutes for your downed server using ext3 to finish fscking your disks, and then when it finishes it tells you you have to reboot also (that use to bring me flashbacks of one "popular" os that always asks for reboots, ahem)... on most of my computers, reiserfs does a check in like in 1 or 2 seconds (literally) and has never asked me for a reboot so far... plus the performance boost compared to ext3 is quite noticeable sometimes.