Do you have the LG 8481B CD-RW drive? I don't recall an 8141B.
1. Are you clicking on the DirectCD icon in the systray? The fact that you are only getting 40x write speeds may be due to the fact that your drive doesn't think the media can be written to at 48x. This can be true even if the media says 48x on it. You could try updating your firmware to improve the drive's media recognition capability.
2. I'm not sure if the packet writing with CD-Rs should spin up and down like that; I only packet-write with CD-RWs. However, it shouldn't be taking anywhere near 3 minutes to burn 37MB to CD-R. This may be a DMA-related problem. I'll explain below.
3. In DirectCD 5.3.2, there is no option for me to change the write speed. It just uses whatever speed it wants. I am assuming it is the same with your version.
4. DMA definitely should be checked, especially with an older system like yours (no offense, I own a Celeron-366 machine among others). It makes it so that the computer can transfer data to and from the drive faster.
5. There is a forum at CD Freaks
6. You can read reviews of CD-R media quality at http://www.digitaldolphin.netfirms.com/
I hope this information helps!