Scali:
I was referring to your Silverado. I remember reading very negative reviews about the orb with the two fans, so I avoided it.

I remember reading about the Silverado and also the Swiftech coolers too. Cost is what always kept me away from them, but I wish I could have tried them.

One good and reasonably priced Athlon cooler I've found is the Arctic Cooling Copper Lite Silent 3. I'm mentioning this unit because they're actually still available. It's a great cooler with a major drawback: The fan is a non-standard item that is not easily/cheaply replaced. The guys at Arctic Cooling must think their fans are made of solid gold because getting an official replacement fan for these coolers is very costly. If the fan on mine ever dies, I'll probably just use a dremel to cut the fan off the base with the mounting clips. I can probably just glue a standard 80mm fan onto the base clips for a replacement. Still, that is an ugly hack.

Evert mentioned the Rosewill RCX-Z100 cooler. I purchased one of these as a backup a few years ago, but I haven't had a chance to install and test it yet. It looks like it should be adequate for a Thunderbird 1400.

I wasn't even considering using one of those Orb coolers on the Thunderbird 1400. I was thinking of using either a Arctic Cooling Copper Lite Silent 3 or Rosewill RCX-Z100 on my system. I've used the Rosewill before and it is a very quiet cooler and you can fit a standard 80mm fan on it. I was actually doing some research on what coolers to get for the V5. Unfortuntely, I can't get one of those Vantecs that you suggested. So far I'm leaning towards getting a standard North Bridge Cooler with a fairly quiet 40mm fan. I reckon those Chinese coolers on eBay fit the bill nicely. But unfortunately, you can't really afford to gamble with such a rare piece of hardware.

Replaced most of the capacitors. However the odd sound issues still exist. I didn't expect it the issue to be resolved anyway. So the HDD is still connected to the RAID controller and the CD-ROM to the Sound Blaster 16.

Just noticing the two caps I replaced several years ago! What an amateur I was back then! That was when I lost the ability to solder the joint as nornal so just did it from the top instead. This board is in a bit of a sorry state I must admit. I didn't replace the smaller ones I did'nt have those and either do I wish to spend any money towards it really. But the main ones are done. With a bit of PCB burn (Other mainboards I've replaced caps on has never burn) Here are some pictures of the board and other bits.
Specs

Athlon Thunderbird 1400MHz
512MB (2x256MB PC133 crucial)
40GB ST340015A HDD
Toshiba SD-M1712
Geforce FX5700 256MB (Winfast A360)
Sound Blaster 16 ISA Pnp CT2940
Realtek 8139 PCI ethernet
Dos 6.21, Windows 3.1 (in VGA only) and Windows 98SE On FAT16 and second partition in FAT32