Machine Configuration:
I have assembled a new machine. Its Intel P4 3.0E Ghz HT enabled processor on ASUS P4P800-MX motherboard. I am using onboard graphics and sound. [Motherboard Spec]
Socket 478, Intel865GV, Hyperthreading ready, integrated intel graphics, dualchannel DDR400, 10/100Mbps LAN, Serial ATA
I have put in two 1 GB dual-channel RAM chips (OCZ technologies) in it.

I installed "Redhat Enterprise Linux 4 WS" on it (installation went super slow..took around 3 hours to complete). Now, it takes RHELv4 a whopping 18 MINUTES to boot up. WindowsXP pro (the other OS on this dual boot machine) boots up in less than 30 secs.

Solutions tried
Since my ASUS motherboard is SMP-enabled and my processor is HT enabled, RHELv4 installed an SML kernel and a normal kernel. But I get the same (very poor) performance from RHELv4, no matter which one (of the two kernels) I use to boot it up.
In SMP-kernel case, I confirmed that cat /proc/cpuinfo shows
2 processors being recognized by RHELv4 (even then the bootup takes 18-20 mins.)

I read online about RHEL issues with 1GB+ memory.
So, just to narrow down the issue, I took out these two 1 GB dual-channel RAM chips and put in a regular Kingston 512MB RAM chip
and RHELv4 started booting up in less than a minute. So now I know the problem is with using 1 GB + RAM.

I confirmed (2) by putting back only one 1GB RAM dual-channel RAM chip, and it started super slow (took around 18-20 mins to bootup again). I also tried passing in mem=1024M kernel parameter, but that did not help either. Even though the cat /proc/meminfo shows 1024MB of RAM being recogized by RHELv4.

I did some search online and found some mixed opinions (which I havent tried yet..since I am not sure about them ,
just listing them here and asking for more suggestions..

Should I recompile my kernel with highmem support -
Isn't highmem only suppposed to be used with 4 GB+ ram machines.?

b)Is this slow bootup being caused by the onboard Integrated Intel graphics ?

Any ideas which one of the above two or (any other alternatives) should i try... ? please help as I am running out of my options now.. Thanks in advance for any helpful tips..