mine takes that long to boot as well. i'm not sure what an .mkext is. I've got 1 gb ram. standard 1000he
On your EFI partition's Extra folder (or for that matter automatically in /System/Library for the contents of /System/Library/Extensions folder) there can be an Extensions.mkext file, which is kind of like a cache for the individual .kext files in the Extensions folder.
If an .mkext file exists that is current, the load will be a lot faster, because instead of parsing and loading tons of individual .kext files, the loader just sucks in a single (or in the case of a Hackintosh two) Extenisons.mkext file(s). That's a lot faster.
Also, Leopard with 1GB is pushing it. A 2GB SO-DIMM costs like $25, and is TOTALLY worth it. With 1GB Leopard is a total dog, with 2GB it's OK, with 4GB it's great.
The reason Leopard is faster than Tiger on new hardware and slower than Tiger on old hardware is mostly the fact that Apple did space/time trade-offs, and newer machines (can) have a lot more RAM than older ones, some of which are limited to 1GB, and hence Leopard crawls on these thanks to excessive VM usage, while it flies on newer machines with plenty 'o RAM.
So if you're serious about running Mac OS X on the EeePC 1000HE, go spend $25 on a 2GB RAM stick.
To create a .mkext file in your EFI partition, you have to do something akin to this:
mkdir /tmp/EFI
mount_hfs /dev/disk0s1 /tmp/EFI
cd /tmp/EFI/Extra/Extensions
rm ../Extensions.mkext
chown -R root:wheel *
chmod -R 755 *
kextcache -a i386 -m ../Extensions.mkext *.kext
Assuming you're booted from /dev/disk0s2 and your EFI partition is /dev/disk0s1, etc.
Also, if you're booting with, or your com.apple.boot.plist contains, e.g. the -f boot option, things will go much slower. In other words, boot speed will be slower if you use unnecessary boot options, have too little RAM, or don't use .mkext files.
Lastly: make sure your permissions on the root drive are correct. If not, things like e.g. /System/Library/Caches might get ignored for security reasons, which again means a slower than required boot process.