Sorry about this really long text..but trying to give as much detail as possible
Still a newbie with linux
Configuration of my PC:

Intel Pentium 2.66Ghz
Asus P5RDVM Motherboard with X900 Chipset
XFX's NVidia 6200TC Card
(But using 8400 currently)
One 100MB NIC on PCI slot (Motherboard has another onboard but its faulty.)
Western Digital 160GB SATA
Seagate 20GB PATA

4 Windows partitions on WD dsik with WIndows XP Pro installed on 1st partition

Now I wanted to install BT3 without messing up my XP installation. Still a newbie to Linux and can't just migrate to Linux as yet.

I installed Acronis disk director and made 3 more partitions. One 1Gb for Linux swap , one 12GB ReiserFS for BT3 and made one 6GB empty space

I also installed Acronis boot loader, just to be safe
Now my previous attempts to successfuly make my PC dualbootable failed with BT. So I thought of installing Ubuntu Linux too. First I booted from an Ubuntu CD and installed it on HDD. In installation process I selected use the largest available free space.
It used that 6GB free space to install itself. After installation I rebooted the PC and was promptly greeted with a GRUB menu with booting options for both XP and Ubuntu.

Now its time for BT3.
Booted using Backtrack 3 DVD. Since I had already made partitions I didnt need to make new using fdiask command.
Just used "Install BT to HD " option from its start menu.

The 12Gb ReiserFS partition was /dev/sda5. Used that for installing BT and /dev/sda for installing MBR. Used full install and unchecked "remove from MBR" option. It took like 10-15 minutes for install.

Rebooted and bumped into LILO boot loader of BT.

Ubuntu and Windows nowhere visible.

Booted into BT and logged in using default password.

type "liloconfig" and selected new LILO installatiion

Booted into BT and logged in using default password.
type "liloconfig" and selected new LILO installatiion
In next menu selected Add Windows Installation and added /dev/sda1
For Ubuntu added /dev/sda8 and "dev/sda5" for BT
Note that these sda will differ for different PCs. Could be hda if you have PATA disk or sda 1,2,3 etc may differ.

Saved and rebooted

This time I got Acronis boot loader menu

But with only 2 choices
One Windows XP and other Linux
Selected Linux and got LILO of BT3 . But this time with 3 options. Windows, Ubuntu and backTrack3
ALl working perfectly

Except for one small part..NIC not working properly.
I fill in proper IP address, gateway etc..but cant ping my gateway even.
Turns out both Linux picked up my onboard NIC (it was fried n a lightning storm).
My other NIC Realtek 8139 (this works) wasnt detected by either Linux

I then disabled my onboard NIC from BIOS and booted int BT. This time ifconig sommand showed only the l0 not eth0
I downloaded drivers of that card and tried installing them..but the error is get is

bt sc92031 # make
Makefile:37: *** Linux kernel source not configured - missing config.h. Stop.
I tried running

before running startx. but that didnt help either

I installed other software, openssl, medusa etc and they got installed without any problem