..... if there is no support for this version
You will find support on just about every version of Avast here and support for other anti-virus and firewall stuff in the General Forum.
I recently tried to install Avast 4 free, I restarted my PC, and I couldn't get the resident shield turned on
, Sometimes this is caused by a poor installation and/or a corrupted file.
then when I tried to run the actual scanner, I couldn't get it to load, it had an error
Please make not of any error messages before you come onto the forum. It is a great help in determining the cause of you difficulties. However, I would suspect that you received a "process error code" which only means that Avast could not start the scan engine or similar, or a "server down error" which is part of the Avast update process. Since the program was not running, a proper connection to the Avast server could not be attained.
My PC's setup is: 566Mhz Celeron 64MB RAM Windows 98SE (All security patches) Internet Explorer 5.5 SP2 (All security patches) The only other programs I had running at the time was DiamondCS's RegProt, and Sygate Personal Firewall 5.5

Your system configuration is more than sufficient to run Avast.

Ah…I see a potential cause. Sygate is very sensitive to allowing connections such as those Avast needs. You must grant Avast access to the internet. You will normally have to give (3) exe files access:
ashServ
ashmaisv
ashdisp

I msyelf am not familiar with Diamond CS but Rej seems to have a grasp on it, so follow his advice with that.

Keep us informed.

Techie