Well, it all depends on what format your camcorder shoots in, and what specifications your computer has. If your camera films in AVCHD, that is currently the most difficult format on the consumer market, and requires a fairly powerful computer both to play it smoothly and to edit it. That requires at least a decent Core 2 Duo, or preferably something more powerful. But X5 also has SmartProxy, which creates standard definition proxies or copies of the HD original. That makes it easier to edit and preview, and when satisfied, the edits are applied to the HD.
If your camcorder also films in full progressive mode i.e. 50 (PAL) or 60 (NTSC) full frames a second, X5 can handle it.
Some HD camcorders, though, film directly in .mp4 or even HD .mov format, and each of these cause problems for some VS users.
I personally still prefer the HDV format, which is much easier to edit than the other HD formats. It uses small tapes just like the 'old' DV/AVI. Unfortunately, though, this format appears to be fading from the consumer domain, but at least is being retained at the professional end of the market -- which is a comment in its own right about the value of the format.