startx is the right command to start your desktop from a command line prompt. If you have in fact install gnome or kde, then it appears that the installation of X was not complete.
execve failed for /etc/X11/X (err no 2)
This error means that no such file was discovered. It appears that X did not completely install.
The file /etc/X11/X which shoud be a symbolic link to the X server, does not exist. It implies that your X installation is not complete, the configuration program has not made the correct link. Most of the time this is the last thing the configuration program does. You try to complete this symbolic link manually, but I am not sure which X server that distro uses.
This, of course, is where your system is trying to boot into Windows. During installation, do you remember where you installed the GRUB bootloader? With one drive partitioned into one partition for each operating system, you should install GRUB to the MBR (Master Boot Record). It appears that GRUB is not installed in MBR.
Since you have not started using the Linux system yet, it may me easier to just reinstall as you did in the beginning, but paying particular attention to installing GRUB to the MBR.
I wish I could offer something quick and easy, but it looks like there is a lot of missing files in your installation.