64 bit downloading and kernel upgrade problem

["Arvind Marathe" <arvind@mbu.iisc.ernet.in>]

Hi all,
Few months back, i first started fiddling around with linux and debian.
Now that i am a little more experienced and have got some free time, i
decided to make my system more efficient. Earlier i had installed a lot of
unnecessary things (whole of gnome and kde etc) and it was not working at
full efficiency. My motherboard is intel915 with 3.4G processor and 1G
RAM. So initially i did a clean install by downloading minimum bootable
i386 stable version from net, copying it on a cd and installing it. I only
loaded x-window system and it was quite fast. Now since hyperthreading is
allowed on my system, i was told ia64 debian version should work and also
give better performance, so i downloaded that from the same site. However
when i copy this on a cd and try to boot, it says:

Reboot and select proper boot device
or Insert Boot Media in selected boot device

This happened for both netinst image and business card image. Any ideas
why this would be happening? I would like to upgrade to 64 bit if
possible. (I downloaded both i386 and ia64 images from the site:
http://www.debian.org/CD/netinst/
but i386 version works, ia64 doesn't)

So i went back to i386 and decided to upgrad my kernel because 'dmesg'
always warned that 'memory usage was not optimal, only 896M would be used,
upgrade kernel.' I used 'apt-get install' to install appropriate kernel
version 2.6.x (earlier was 2.4.x) but when i try to boot using this
version, i get 'kernel panic' message...also it shows some scsi disk
errors, but i have no scsi disks. The entries in /boot/grub/menu.1st seem
fine (i.e. it shows /dev/hda1 for root filesystem which is what i have).
Is there anything else i need to do? I did try some things suggested
online but didn't work.

So basically i need guidance on two things:
1> Can i use 64 bit version on my machine? would that improve performance?
2> How to upgrade kernel?

Thanks and Regards,
Arvind