your own personal preference..if you have the money or w/e then go ahead and buy yourself a piece of hardware. =P

Reasons for having a hardware synth in your setup can be varied, but I recommend it for some:

1. It could be for a specific sound you are looking for (aka the Mr. Clean sound of the Supernova; supersaw-nazis and their JP-80xxs -- okay, now I'm one)

2. CPU power isn't going to creating a sound... just recieving it (Thank goodness for ASIO). That's a definate plus for people who sweat how much the CPU bar goes up with each VST addon.

3. Hands on control (toys are fun).

I dunno about hardware drum machines... I think that sampled software drum machines are about as good as it gets (aka Battery).

___________________
Audio-s

upside of hardware:
1. Sound quality if used to it's potential.
2. Hands on feel and "tweakability"
Downside of Hardware
1. Price
2. Lack of integration (although if you have a Virus Ti that works, I guess this is solved). It's nice to fire up your computer and have everything running in one screen.
3. Lack of mulitple instances. You only get one. You need to record to audio in order to start another patch playing. Yes, you can run mulitple sounds on some synths, but for example, on the virus, fx are universal across all sounds in multi mode, so it's not really a multi-mode is it.

If you have the money, then go for it. They're great fun and no matter what all the soft synth users say, short of romplers sampled from hardware, there are't any soft synths that don't require a DSP chip that can match them, when used correctly. Having said that, you can still get a good sound out of software. I use ABL and Atmopshere all the time, quality VSTi's.

___________________
1 out of every 4 people in this country are mentally disturbed. Look at your 3 closest friends. If they seem okay, then you're the one.