Consider that the price of a children's comic is closing in on £2 and you can't really query the £4.99 GSP is asking for in exchange for this CD-ROM tie-in. True, the content is uninspired, obvious and limited in its engagement, but there's still a breadth of things to do, and our infant test subject just about squeezed a fiver's worth of fun from it.

The CD-ROM is based around the CBeebies programme of the same name, set in and around the London Underground system. Think a less inspired, glossier looking Thomas The Tank Engine if you're after any kind of parallel. To be fair, the tie-in to the programme is handled very well. The music and visuals are strictly and carefully in line with the show, and from a multimedia standpoint, it's very well done.

Still, it wasn't as straightforward to install on our test machine as we'd have liked, courtesy of a problem with .Net framework issues. The software requires .Net to be in place and will install it if it can't find it. It took some manual fiddling on our part before we could get it to work, too.

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This aside, we soon found ourselves at a bright screen of activities, straight out of the Kids CD-ROM Construction Kit. A word search, for instance, was as simple as it sounds, while there's a neat if brief chance to meet all the characters from the show via point-and-click. Pairs, meanwhile, is a simple task of turning over two cards at a time, and trying to pair them off before the clock runs down.

The jigsaws, fun as they are, are self-explanatory, while the colouring-in section throws up some pictures to print off and allow your anklebiter to get to work on. Then there's sliding tiles, which comes with variable levels of difficulty from very, very easy to surprisingly hard. It's then rounded off with a spot-the-difference segment that our pint-sized tester found a little too pernickety, with some differences very easy to spot but one or two determinedly less so.

There's little spark to all of this, but it's still hard to complain that you don't get some half-decent software for your money. Plus our testing recruit, while never enthralled, was kept quiet for an hour or so fairly easily.

Ultimately though, the activities provided on the disc are what we've come to expect from a well specified tie-in Web site now, as the CBeebies' own online pages have shown. There's certainly nothing radical or taxing here, but in some ways the program is compromised by just how much quality content the BBC is giving away for free online. Thus, Underground Ernie is a decent budget CD-ROM, but rivalled by software that costs £4.99 less.

A competent tie-in and one that routinely ticks the boxes it's asked to tick. But the BBC Web site does much of this, too.